cmake SYS_TYPES_H_HAS_PID_T examples

m-a-d-n-e-s-s/madness CMakeLists.txt :495 

check_cxx_source_compiles(
    "
    #include <sys/types.h>
    int main() { typedef pid_t test_t; return 0; }
    " SYS_TYPES_H_HAS_PID_T)