patch for crash in d-lang.c's demangler

[Brad Roberts <braddr@puremagic.com>]

There's a minor, but important bug in the d language symbol demangler.  I
haven't reviewed the whole thing for other bugs, just the one that I hit.

I don't have a copyright assignment form on file, but hopefully this diff is
small enough to not require one.  Consider the patch public domain or whatever
if that helps.

diff --git a/gdb/d-lang.c b/gdb/d-lang.c
index 6db521b..f17431b 100644
--- a/gdb/d-lang.c
+++ b/gdb/d-lang.c
@@ -37,8 +37,9 @@ extract_identifiers (const char *mangled_str, struct obstack
*tempbuf)

   while (isdigit (*mangled_str))
     {
-      i = strtol (mangled_str, NULL, 10);
-      mangled_str++;
+      char * end_ptr;
+      i = strtol (mangled_str, &end_ptr, 10);
+      mangled_str = end_ptr;
       if (i <= 0  && strlen (mangled_str) < i)
         return 0;
       obstack_grow (tempbuf, mangled_str, i);

Before this change, symbols with string fragments over 9 bytes long gets into a
bad state and might end up crashing.  Certainly ends up with a bad string.

And example that crashes for me:
    20src/core/atomic.d.9215__unittest_failFiZv

Thanks,
Brad