[ob] Fix dwarf2 reader crash

[Mark Kettenis <mark.kettenis@xs4all.nl>]

DW_AT_decl_file can be zero, indicating no file.  It's better not to
crash in that case.

Mark


Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>

	* dwarf2read.c (new_symbol): Handle DW_AT_decl_file being zero.

Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.213
diff -u -p -r1.213 dwarf2read.c
--- dwarf2read.c 23 Jan 2007 23:57:47 -0000 1.213
+++ dwarf2read.c 28 Jan 2007 14:39:55 -0000
@@ -7079,7 +7079,7 @@ new_symbol (struct die_info *die, struct
 	      || file_index > cu->line_header->num_file_names)
 	    complaint (&symfile_complaints,
 		       _("file index out of range"));
-	  else
+	  else if (file_index > 0)
 	    {
 	      struct file_entry *fe;
 	      fe = &cu->line_header->file_names[file_index - 1];