Determining if the include file pthread.h exists failed with the following output:
Change Dir: /nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_56bf5/fast && make[1]: Entering directory '/nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp'
/usr/bin/make  -f CMakeFiles/cmTC_56bf5.dir/build.make CMakeFiles/cmTC_56bf5.dir/build
make[2]: Entering directory '/nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_56bf5.dir/CheckIncludeFile.c.o
/nvme/rc-buildroot-test/scripts/instance-1/output-1/host/bin/arm-linux-gcc --sysroot=/nvme/rc-buildroot-test/scripts/instance-1/output-1/host/arm-buildroot-linux-uclibcgnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -o CMakeFiles/cmTC_56bf5.dir/CheckIncludeFile.c.o   -c /nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp/CheckIncludeFile.c
/nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp/CheckIncludeFile.c:1:10: fatal error: pthread.h: No such file or directory
    1 | #include <pthread.h>
      |          ^~~~~~~~~~~
compilation terminated.
CMakeFiles/cmTC_56bf5.dir/build.make:68: recipe for target 'CMakeFiles/cmTC_56bf5.dir/CheckIncludeFile.c.o' failed
make[2]: *** [CMakeFiles/cmTC_56bf5.dir/CheckIncludeFile.c.o] Error 1
make[2]: Leaving directory '/nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp'
Makefile:124: recipe for target 'cmTC_56bf5/fast' failed
make[1]: *** [cmTC_56bf5/fast] Error 2
make[1]: Leaving directory '/nvme/rc-buildroot-test/scripts/instance-1/output-1/build/bullet-3.09/CMakeFiles/CMakeTmp'