[unique] build: Fix typo

[Emmanuele Bassi <ebassi src gnome org>]

commit 44a91545d7c72520abf202f0f164735a3bacb588
Author: Emmanuele Bassi <ebassi linux intel com>
Date:   Sun Mar 27 09:55:58 2011 +0100

    build: Fix typo
    
    There is an extra $ in the default handler for the --enable-debug
    argument, and it has broken the assignment of the default value in case
    the argument is not specified.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index fba423f..b56a10d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -207,7 +207,7 @@ AC_ARG_ENABLE([debug],
               [AC_HELP_STRING([--enable-debug=@<:@no/minimum/yes@:>@],
                               [Turn on debugging @<:@default=debug_default@:>@])],
               [],
-              [enable_debug=$debug_default])
+              [enable_debug=debug_default])
 
 AS_CASE([$enable_debug],