[PATCH] Fix bootstrap with GCC 4.2.1 (PR82939)

[Richard Biener]

After Jakubs fixes we can restore bootstrap with GCC 4.2.1 as provided
by older Darwin hosts with the following patch.

Bootstrap using a GCC 4.2.1 host compiler on x86_64-unknown-linux-gnu
is now in stage2.

Ok for trunk?

Thanks,
Richard.

2018-02-16  Richard Biener  <rguent...@suse.de>

        PR bootstrap/82939
        * line-map.c (linemap_init): Avoid broken value-init when compiling
        with GCC 4.2.

Index: libcpp/line-map.c
===================================================================
--- libcpp/line-map.c   (revision 257728)
+++ libcpp/line-map.c   (working copy)
@@ -344,7 +344,12 @@ void
 linemap_init (struct line_maps *set,
              source_location builtin_location)
 {
+#if __GNUC__ == 4 && __GNUC_MINOR__ == 2
+  /* PR33916, needed to fix PR82939.  */
+  memset (set, 0, sizeof (struct line_maps));
+#else
   *set = line_maps ();
+#endif
   set->highest_location = RESERVED_LOCATION_COUNT - 1;
   set->highest_line = RESERVED_LOCATION_COUNT - 1;
   set->location_adhoc_data_map.htab =