MDEV-33616: Detect select() on macOS

macOS declares select() in sys/select.h, which the HAVE_SELECT probe did
not include.  clang rejects a call to an undeclared function, so the
probe failed and HAVE_SELECT was left undefined.

my_sleep() then took its last fallback, a busy loop on time() that
rounds the requested interval up to a whole second.  Every sub-second
sleep in the server became a one second spin on a CPU, which is what
made rpl.rpl_perfschema_applier_status_by_worker,
rpl.rpl_shutdown_sighup and rpl.rpl_semi_sync_shutdown_await_ack fail.

configure.cmake

@@ -590,6 +590,8 @@ CHECK_C_SOURCE_COMPILES("
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netdb.h>
+/* macOS declares select() here and nowhere else that this test includes */
+#include <sys/select.h>
 #endif
 int main()
 {