Merge variable declaration and export.

Originally committed as revision 15554 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -8,8 +8,7 @@
 #
 
 # Prevent locale nonsense from breaking basic text processing.
-LC_ALL=C
-export LC_ALL
+export LC_ALL=C
 
 # make sure we are running under a compatible shell
 # try to make this part work with most shells