[google] Normalize version number for google/gcc-4_6 (issue4454049)

[Diego Novillo]

Since google/gcc-4_6 follows the 4.6 branch, changes in minor
revisions cause unnecessary churn in directory names.

Fixed with this.  OK for google/gcc-4_6?

        Google ref 4335466.

        * BASE-VER: Change to 4.6.x-google.

diff --git a/gcc/BASE-VER b/gcc/BASE-VER
index 4110f74..33d4edd 100644
--- a/gcc/BASE-VER
+++ b/gcc/BASE-VER
@@ -1 +1 @@
-4.6.1-google
+4.6.x-google

--
This patch is available for review at http://codereview.appspot.com/4454049