Performing C SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_fde75/fast && make[1]: Entering directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_fde75.dir/build.make CMakeFiles/cmTC_fde75.dir/build
make[2]: Entering directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_fde75.dir/src.c.o
/tmp/instance-1/output-1/host/bin/arm-linux-gnueabihf-gcc --sysroot=/tmp/instance-1/output-1/host/arm-buildroot-linux-gnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -D_FORTIFY_SOURCE=1 -DCMAKE_HAVE_LIBC_PTHREAD  -DNDEBUG   -o CMakeFiles/cmTC_fde75.dir/src.c.o   -c /tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp/src.c
Linking C executable cmTC_fde75
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_fde75.dir/link.txt --verbose=1
/tmp/instance-1/output-1/host/bin/arm-linux-gnueabihf-gcc --sysroot=/tmp/instance-1/output-1/host/arm-buildroot-linux-gnueabihf/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -D_FORTIFY_SOURCE=1 -DCMAKE_HAVE_LIBC_PTHREAD  -DNDEBUG    CMakeFiles/cmTC_fde75.dir/src.c.o  -o cmTC_fde75 
CMakeFiles/cmTC_fde75.dir/src.c.o: In function `main':
src.c:(.text.startup+0x14): undefined reference to `pthread_create'
src.c:(.text.startup+0x1c): undefined reference to `pthread_detach'
src.c:(.text.startup+0x28): undefined reference to `pthread_join'
src.c:(.text.startup+0x38): undefined reference to `pthread_atfork'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_fde75.dir/build.make:87: cmTC_fde75] Error 1
make[2]: Leaving directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_fde75/fast] Error 2
make[1]: Leaving directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'


Source file was:
#include <pthread.h>

void* test_func(void* data)
{
  return data;
}

int main(void)
{
  pthread_t thread;
  pthread_create(&thread, NULL, test_func, NULL);
  pthread_detach(thread);
  pthread_join(thread, NULL);
  pthread_atfork(NULL, NULL, NULL);
  pthread_exit(NULL);

  return 0;
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_5be1d/fast && make[1]: Entering directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_5be1d.dir/build.make CMakeFiles/cmTC_5be1d.dir/build
make[2]: Entering directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_5be1d.dir/CheckFunctionExists.c.o
/tmp/instance-1/output-1/host/bin/arm-linux-gnueabihf-gcc --sysroot=/tmp/instance-1/output-1/host/arm-buildroot-linux-gnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -D_FORTIFY_SOURCE=1 -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG   -o CMakeFiles/cmTC_5be1d.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.16/Modules/CheckFunctionExists.c
Linking C executable cmTC_5be1d
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_5be1d.dir/link.txt --verbose=1
/tmp/instance-1/output-1/host/bin/arm-linux-gnueabihf-gcc --sysroot=/tmp/instance-1/output-1/host/arm-buildroot-linux-gnueabihf/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -D_FORTIFY_SOURCE=1 -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG    CMakeFiles/cmTC_5be1d.dir/CheckFunctionExists.c.o  -o cmTC_5be1d  -lpthreads 
/tmp/instance-1/output-1/host/opt/ext-toolchain/bin/../lib/gcc/arm-linux-gnueabihf/7.3.1/../../../../arm-linux-gnueabihf/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_5be1d.dir/build.make:87: cmTC_5be1d] Error 1
make[2]: Leaving directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_5be1d/fast] Error 2
make[1]: Leaving directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'



Performing C SOURCE FILE Test COMPILER_HAS_HIDDEN_INLINE_VISIBILITY failed with the following output:
Change Dir: /tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_87965/fast && make[1]: Entering directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_87965.dir/build.make CMakeFiles/cmTC_87965.dir/build
make[2]: Entering directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_87965.dir/src.c.o
/tmp/instance-1/output-1/host/bin/arm-linux-gnueabihf-gcc --sysroot=/tmp/instance-1/output-1/host/arm-buildroot-linux-gnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -D_FORTIFY_SOURCE=1 -DCOMPILER_HAS_HIDDEN_INLINE_VISIBILITY  -DNDEBUG   -fvisibility-inlines-hidden -o CMakeFiles/cmTC_87965.dir/src.c.o   -c /tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp/src.c
cc1: warning: command line option '-fvisibility-inlines-hidden' is valid for C++/ObjC++ but not for C
Linking C executable cmTC_87965
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_87965.dir/link.txt --verbose=1
/tmp/instance-1/output-1/host/bin/arm-linux-gnueabihf-gcc --sysroot=/tmp/instance-1/output-1/host/arm-buildroot-linux-gnueabihf/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -D_FORTIFY_SOURCE=1 -DCOMPILER_HAS_HIDDEN_INLINE_VISIBILITY  -DNDEBUG    CMakeFiles/cmTC_87965.dir/src.c.o  -o cmTC_87965 
make[2]: Leaving directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'
make[1]: Leaving directory '/tmp/instance-1/output-1/build/librtlsdr-d794155ba65796a76cd0a436f9709f4601509320/CMakeFiles/CMakeTmp'


Source file was:
int main(void) { return 0; }