Fix mma/mmma by making gettop canonicalize TOP when set

Bug: 17253957

(cherry picked from commit a5c4f178ae)

Change-Id: Id5f5a6e9c81d4332ef5a846423ea41384a053db6

envsetup.sh

@@ -606,7 +606,8 @@ function gettop
 {
     local TOPFILE=build/core/envsetup.mk
     if [ -n "$TOP" -a -f "$TOP/$TOPFILE" ] ; then
-        echo $TOP
+        # The following circumlocution ensures we remove symlinks from TOP.
+        (cd $TOP; PWD= /bin/pwd)
     else
         if [ -f $TOPFILE ] ; then
             # The following circumlocution (repeated below as well) ensures