Resovle symlink in findmakefiles in envsetup.sh

So the returned path can match the one returned by gettop,
and so we can get the correct relative path of ONE_SHOT_MAKEFILE when running mm.

Change-Id: I492d68fec47e59ec9f4ea0fb5139b1a28af0f6cd

envsetup.sh

@@ -616,7 +616,7 @@ function findmakefile()
     local HERE=$PWD
     T=
     while [ \( ! \( -f $TOPFILE \) \) -a \( $PWD != "/" \) ]; do
-        T=$PWD
+        T=`PWD= /bin/pwd`
         if [ -f "$T/Android.mk" ]; then
             echo $T/Android.mk
             cd $HERE > /dev/null