Determining if the include file pthread.h exists failed with the following output:
Change Dir: /accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_9735e/fast"
make[1]: Entering directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_9735e.dir/build.make CMakeFiles/cmTC_9735e.dir/build
make[2]: Entering directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_9735e.dir/CheckIncludeFile.c.o
/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/host/bin/arm-linux-gcc --sysroot=/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/host/arm-buildroot-linux-uclibcgnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -o CMakeFiles/cmTC_9735e.dir/CheckIncludeFile.c.o   -c /accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp/CheckIncludeFile.c
/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp/CheckIncludeFile.c:1:21: fatal error: pthread.h: No such file or directory
 #include <pthread.h>
                     ^
compilation terminated.
make[2]: *** [CMakeFiles/cmTC_9735e.dir/CheckIncludeFile.c.o] Error 1
make[2]: Leaving directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp'
make[1]: *** [cmTC_9735e/fast] Error 2
make[1]: Leaving directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/optee-client-3.4.0/CMakeFiles/CMakeTmp'