Added prune options to findleaves.sh to ignore the .git and .repo
directories since the Android.mk files will not be found in these
directories.

Prunning out these directories decreased the make parse by nearly
a minute on a cold cache and eliminated 60,000+ stats on files in
the .git and .repo directories.
diff --git a/core/main.mk b/core/main.mk
index aaf5a76..97e49f4 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -422,7 +422,7 @@
 # Can't use first-makefiles-under here because
 # --mindepth=2 makes the prunes not work.
 subdir_makefiles += \
-	$(shell build/tools/findleaves.sh --prune="./out" $(subdirs) Android.mk)
+	$(shell build/tools/findleaves.sh --prune="*\.git*" --prune="*\.repo*" --prune="./out" $(subdirs) Android.mk)
 
 # Boards may be defined under $(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)
 # or under vendor/*/$(TARGET_DEVICE).  Search in both places, but