Define _XOPEN_SOURCE instead of __USE_XOPEN for strptime

According to man strptime page _XOPEN_SOURCE is the correct macro,
not __USE_XOPEN

src/utils/utils.c

@@ -7,12 +7,11 @@
  *
  */
 
+#define _DEFAULT_SOURCE
+#define _XOPEN_SOURCE
 #include <stdio.h>
 #include <string.h>
 #include <signal.h>
-#ifndef __GLIBC__
-#define __USE_XOPEN
-#endif
 #include <time.h>
 #include <unistd.h>
 #include <sys/types.h>