[libbacktrace] Fix warning as error in btest.c and hence `make test`

[Gerald Pfeifer]

Running `make test` on my nightly testers I noticed the following
in the log files:

cc1: warnings being treated as errors
/scratch/tmp/gerald/gcc-HEAD/libbacktrace/btest.c: In function 'f23':
/scratch/tmp/gerald/gcc-HEAD/libbacktrace/btest.c:476: warning: 'expected' may 
be used uninitialized in this function
gmake[3]: *** [btest-btest.o] Error 1
gmake[3]: Target `btest' not remade because of errors.

Doesn't this mean that effectively the test is not executed?

In any case the patch below addresses this.  Bootstrapped and
tested on i386-unknown-freebsd10.0.

Ok?

Gerald


2012-10-04  Gerald Pfeifer  <ger...@pfeifer.com>

        * btest.c (f23): Avoid uninitialized variable warning.

Index: btest.c
===================================================================
--- btest.c     (revision 192086)
+++ btest.c     (working copy)
@@ -486,7 +486,7 @@
                case 2:
                  expected = "test3";
                  break;
-               case 3:
+               default:
                  assert (0);
                }