cmake HAVE_FDCLOSE examples

JulNadeauCA/libagar CMakeChecks.cmake :1236

check_c_source_compiles("
#include <stdio.h>
int
main(int argc, char *argv[])
{
	FILE *f = fopen(\"/dev/null\",\"r\");
	int fdp;

	return fdclose(f, &fdp);
}
" HAVE_FDCLOSE)