gdb/

* symfile.c (addr_info_make_relative): Extend comment.  Move SECT to
	a more inner block.  Initialize ADDR by LOWER_OFFSET only if it was
	found by bfd_get_section_by_name.
	* symfile.h (struct section_addr_info) <sectindex>: New comment.

gdb/symfile.h

@@ -80,6 +80,8 @@ struct section_addr_info
   {
     CORE_ADDR addr;
     char *name;
+
+    /* SECTINDEX must be valid for associated BFD if ADDR is not zero.  */
     int sectindex;
   } other[1];
 };