Fix build on GCC older than 4.6.0 which does not allow #pragma GCC diagnostic

inside of functions.

PR: 242693

--- lib/iso9660/iso9660.c.orig	2019-04-13 15:15:15 UTC

+++ lib/iso9660/iso9660.c

@@ -373,12 +373,18 @@ iso9660_set_ltime_with_timezone(const struct tm *p_tm,

   if (!p_tm) return;

+#if defined(__GNUC__) && __GNUC__ >= 5

+#pragma GCC diagnostic push

 #pragma GCC diagnostic ignored "-Wformat-truncation"

+#endif

   snprintf(_pvd_date, 17,

            "%4.4d%2.2d%2.2d" "%2.2d%2.2d%2.2d" "%2.2d",

            p_tm->tm_year + 1900, p_tm->tm_mon + 1, p_tm->tm_mday,

            p_tm->tm_hour, p_tm->tm_min, p_tm->tm_sec,

            0 /* 1/100 secs */ );

+#if defined(__GNUC__) && __GNUC__ >= 5

+#pragma GCC diagnostic pop

+#endif

   /* Set time zone in 15-minute interval encoding. */

   pvd_date->lt_gmtoff -= (time_zone / 15);