Fix seg-fault when running garbage collection on coff binaries.

PR ld/20401
	* coffgen.c (fini_reloc_cookie_rels): Check for the extistence
	of the coff_section_data before using it.

bfd/ChangeLog

@@ -1,3 +1,10 @@
+2016-07-27  Ozkan Sezer  <sezeroz@gmail.com>
+	    Nick Clifton  <nickc@redhat.com>
+
+	PR ld/20401
+	* coffgen.c (fini_reloc_cookie_rels): Check for the extistence
+	of the coff_section_data before using it.
+
 2016-07-26  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* elfxx-mips.c (mips_elf_calculate_relocation): Handle branches

bfd/coffgen.c

@@ -2691,7 +2691,13 @@ static void
 fini_reloc_cookie_rels (struct coff_reloc_cookie *cookie,
 			asection *sec)
 {
-  if (cookie->rels && coff_section_data (NULL, sec)->relocs != cookie->rels)
+  if (cookie->rels
+      /* PR 20401.  The relocs may not have been cached, so check first.
+	 If the relocs were loaded by init_reloc_cookie_rels() then this
+	 will be the case.  FIXME: Would performance be improved if the
+	 relocs *were* cached ?  */
+      && coff_section_data (NULL, sec)
+      && coff_section_data (NULL, sec)->relocs != cookie->rels)
     free (cookie->rels);
 }