Avoid triggering Solaris header bug 23506995 when an old XPG version is
requested in a C99 or later mode of the C compiler.

Need to figure out how best to submit upstream.

--- file-roller-3.16.4/src/fr-command-unarchiver.c
+++ file-roller-3.16.4/src/fr-command-unarchiver.c
@@ -20,8 +20,10 @@
  */
 
 #include <config.h>
+#ifndef __sun
 #define _XOPEN_SOURCE       /* See feature_test_macros(7) */
 #define _XOPEN_SOURCE_EXTENDED 1  /* for strptime */
+#endif
 #include <time.h>
 #include <stdio.h>
 #include <stdlib.h>