Determining if the pthread_create exist failed with the following output:
Change Dir: /tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_f6275/fast"
make[1]: Entering directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_f6275.dir/build.make CMakeFiles/cmTC_f6275.dir/build
make[2]: Entering directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_f6275.dir/CheckSymbolExists.c.o
/tmp/instance-0/output-1/host/bin/nios2-linux-gcc --sysroot=/tmp/instance-0/output-1/host/nios2-buildroot-linux-gnu/sysroot -D_GNU_SOURCE -D_LARGEFILE64_SOURCE  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -std=iso9899:1990 -fno-common -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wmissing-format-attribute -Wwrite-strings -Werror=implicit-function-declaration   -DNDEBUG   -o CMakeFiles/cmTC_f6275.dir/CheckSymbolExists.c.o   -c /tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_f6275
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_f6275.dir/link.txt --verbose=1
/tmp/instance-0/output-1/host/bin/nios2-linux-gcc --sysroot=/tmp/instance-0/output-1/host/nios2-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -std=iso9899:1990 -fno-common -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wmissing-format-attribute -Wwrite-strings -Werror=implicit-function-declaration   -DNDEBUG    CMakeFiles/cmTC_f6275.dir/CheckSymbolExists.c.o  -o cmTC_f6275 
/tmp/instance-0/output-1/host/opt/ext-toolchain/bin/../lib/gcc/nios2-buildroot-linux-gnu/8.3.0/../../../../nios2-buildroot-linux-gnu/bin/ld: CMakeFiles/cmTC_f6275.dir/CheckSymbolExists.c.o: in function `main':
CheckSymbolExists.c:(.text.startup+0x8): undefined reference to `pthread_create'
/tmp/instance-0/output-1/host/opt/ext-toolchain/bin/../lib/gcc/nios2-buildroot-linux-gnu/8.3.0/../../../../nios2-buildroot-linux-gnu/bin/ld: CheckSymbolExists.c:(.text.startup+0x1c): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_f6275.dir/build.make:87: cmTC_f6275] Error 1
make[2]: Leaving directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_f6275/fast] Error 2
make[1]: Leaving directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'

File /tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef pthread_create
  return ((int*)(&pthread_create))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_afb1f/fast"
make[1]: Entering directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_afb1f.dir/build.make CMakeFiles/cmTC_afb1f.dir/build
make[2]: Entering directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_afb1f.dir/CheckFunctionExists.c.o
/tmp/instance-0/output-1/host/bin/nios2-linux-gcc --sysroot=/tmp/instance-0/output-1/host/nios2-buildroot-linux-gnu/sysroot -D_GNU_SOURCE -D_LARGEFILE64_SOURCE  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -std=iso9899:1990 -fno-common -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wmissing-format-attribute -Wwrite-strings -Werror=implicit-function-declaration -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG   -o CMakeFiles/cmTC_afb1f.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.13/Modules/CheckFunctionExists.c
Linking C executable cmTC_afb1f
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_afb1f.dir/link.txt --verbose=1
/tmp/instance-0/output-1/host/bin/nios2-linux-gcc --sysroot=/tmp/instance-0/output-1/host/nios2-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -std=iso9899:1990 -fno-common -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wmissing-format-attribute -Wwrite-strings -Werror=implicit-function-declaration -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG    CMakeFiles/cmTC_afb1f.dir/CheckFunctionExists.c.o  -o cmTC_afb1f -lpthreads 
/tmp/instance-0/output-1/host/opt/ext-toolchain/bin/../lib/gcc/nios2-buildroot-linux-gnu/8.3.0/../../../../nios2-buildroot-linux-gnu/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_afb1f.dir/build.make:87: cmTC_afb1f] Error 1
make[2]: Leaving directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_afb1f/fast] Error 2
make[1]: Leaving directory '/tmp/instance-0/output-1/build/kf5-kcoreaddons-5.47.0/CMakeFiles/CMakeTmp'