cmake _HAVE_SIGPROCMASK examples

Kitware/VTK ThirdParty/hdf5/vtkhdf5/config/cmake_ext_mod/ConfigureChecks.cmake :455 

CHECK_FUNCTION_EXISTS (sigprocmask       ${HDF_PREFIX}_HAVE_SIGPROCMASK)

Tencent/Forward source/third_party/hdf5/config/cmake_ext_mod/ConfigureChecks.cmake :518 

CHECK_FUNCTION_EXISTS (sigprocmask       ${HDF_PREFIX}_HAVE_SIGPROCMASK)