[svn-r28202] HDFFV-9550: Add VS2015 fix for timezone.

CMake test fix for VS2015 print exponent

src/H5Omtime.c

@@ -178,7 +178,13 @@ H5O_mtime_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
     time_t	*mesg, the_time;
     int	i;
     struct tm	tm;
-    void        *ret_value;     /* Return value */
+    void        *ret_value = NULL;      /* Return value */
+#if _MSC_VER >= 1900  // VS 2015
+// In gcc and in Visual Studio prior to VS 2015 'timezone' is a global
+// variable declared in time.h. That variable was deprecated and in VS 2015
+// is removed, with _get_timezone replacing it.
+    long timezone = 0;
+#endif
 
     FUNC_ENTER_NOAPI_NOINIT
 
@@ -219,6 +225,9 @@ H5O_mtime_decode(H5F_t H5_ATTR_UNUSED *f, hid_t H5_ATTR_UNUSED dxpl_id, H5O_t H5
     /* BSD-like systems */
     the_time += tm.tm_gmtoff;
 #elif defined(H5_HAVE_TIMEZONE)
+    #if _MSC_VER >= 1900  // VS 2015
+        HDget_timezone(&timezone);
+    #endif
     /* GNU/Linux systems */
     the_time -= timezone - (tm.tm_isdst ? 3600 : 0);
 #else