FYI: HEAD: fix computation of filename extension in try_dlopen

[Ralf Wildenhues]

In the mdemo test, with
  ./mdemo nonexistent

I currently get 
| can't open the module asd!
| error was: not enough memory

instead of the expected "file not found" error.  The patch below should
fix this to be
| error was: file not found

by avoiding to substract a pointer from the NULL pointer.

This code seems to me not present in branch-1-5.

Cheers,
Ralf

2007-09-01  Ralf Wildenhues  <address@hidden>

        * libltdl/ltdl.c (try_dlopen): Fix computation of extension,
        avoids subtracting pointer from NULL pointer.

Index: libltdl/ltdl.c
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/ltdl.c,v
retrieving revision 1.260
diff -u -r1.260 ltdl.c
--- libltdl/ltdl.c      1 Sep 2007 08:13:20 -0000       1.260
+++ libltdl/ltdl.c      1 Sep 2007 10:20:10 -0000
@@ -1209,11 +1209,11 @@
 
   assert (base_name && *base_name);
 
+  ext = strrchr (base_name, '.');
   if (!ext)
     {
       ext = base_name + LT_STRLEN (base_name);
     }
-  ext = strrchr (base_name, '.');
 
   /* extract the module name from the file name */
   name = MALLOC (char, ext - base_name + 1);