cmake CMAKE_HAVE_LIBC_CREATE examples

plumonito/dtslam 3rdparty/gflags-2.1.1/cmake/FindThreadsCXX.cmake :62 

CHECK_CXX_SYMBOL_EXISTS(pthread_create pthread.h CMAKE_HAVE_LIBC_CREATE)

CatxFish/obs-virtual-cam cmake/Modules/FindThreads.cmake :80 

check_symbol_exists(pthread_create pthread.h CMAKE_HAVE_LIBC_CREATE)