Add percent library to support libraries build.

Change-Id: I8d54f4249f609032fde1d015900204e284fc0c60
diff --git a/core/pathmap.mk b/core/pathmap.mk
index 137b5d5..dfde4ce 100644
--- a/core/pathmap.mk
+++ b/core/pathmap.mk
@@ -115,7 +115,8 @@
         v8/renderscript \
         v13 \
         v17/leanback \
-        design
+        design \
+        percent
 
 #
 # A list of all source roots under frameworks/multidex.