cmake HAVE_SC_NPROCESSORS_ONLN examples

GenericMappingTools/gmt cmake/modules/ConfigureChecks.cmake :229 

check_c_source_compiles (
			"
			#include <unistd.h>
			int main() {
			  sysconf(_SC_NPROCESSORS_ONLN);
			}
			"
			HAVE_SC_NPROCESSORS_ONLN)