Fix dx to match the new SDK structure.

(cherry picked from commit cb9dfa123c6fcc43be629666837c4e6f86b476ea)

Change-Id: I071d73adc4a2eb812cdbc204d27884f4a527043d
diff --git a/dx/etc/dx b/dx/etc/dx
index e5cedff..632af43 100644
--- a/dx/etc/dx
+++ b/dx/etc/dx
@@ -39,7 +39,7 @@
 
 if [ ! -r "$libdir/$jarfile" ]; then
     # set dx.jar location for the SDK case
-    libdir=`dirname "$progdir"`/platform-tools/lib
+    libdir="$libdir/lib"
 fi