Proguard default config file.

It is located in $SDK/tools/lib/proguard.cfg and automatically
put in Ant project (create and update if project is not already setup
for proguard).

Change-Id: I9bcb2a5aafec1329b0c001799f4ba34c61569c3a
diff --git a/build/tools.atree b/build/tools.atree
index 55ad757..e9810fb 100644
--- a/build/tools.atree
+++ b/build/tools.atree
@@ -51,6 +51,7 @@
 # sdk.git Ant templates for project build files
 sdk/templates/build.template        tools/lib/build.template
 sdk/templates/build.export.template tools/lib/build.export.template
+sdk/files/proguard.cfg              tools/lib/proguard.cfg
 
 # Ant Build Rules
 sdk/files/ant                       tools/ant