Remove sgGMTime, no longer used.

(And the implementation was wrong on Windows)

simgear/timing/lowleveltime.cxx

@@ -1134,24 +1134,3 @@ char *tzstring (const char* string)
 
   return strncpy (p, string, needed);
 }
-
-time_t sgGMTime()
-{
-    // this was created to fix:
-    // https://code.google.com/p/flightgear-bugs/issues/detail?id=1207
-    // however applying the code on Unix causes bug:
-    // https://code.google.com/p/flightgear-bugs/issues/detail?id=1301
-    // One solution would be to deinfe our own 'timegm' as suggested here:
-    // http://linux.die.net/man/3/timegm
-    // but for the moment we'll assume time(0) on Unix is UTC, and hence we
-    // return it directly.
-
-	time_t now_sec = time(0);
-#if defined(SG_WINDOWS)
-    struct tm now;
-	now = *gmtime(&now_sec);
-    return mktime(&now);
-#else
-	return now_sec;
-#endif
-}

simgear/timing/lowleveltime.h

@@ -41,11 +41,6 @@ void show (const char *zone, time_t t, int v);
 /* adapted from <time.h> */
 struct tm * fgLocaltime (const time_t *t, const char *tzName);
 
-/* version of time() which returns a value in GMT/UTC, without 
- any timezone adjustment. Necessary on Windows where calling time()
- returns a value in the local time-zone. */
-time_t sgGMTime();
-
 /* Prototype for the internal function to get information based on TZ.  */
 extern struct tm *fgtz_convert (const time_t *t, int use_localtime,
 				     struct tm *tp, const char *tzName);