Add tidy.mk to set up global default checks.

* Default checks include only google* minus google-readability*.
* Some google-* checks are disabled for external projects.
* Each project can add more or disable checks through LOCAL_TIDY_CHECKS.

Bug: http://b/27779618
Change-Id: I83eed73bd2bddaace565a6dde532fb2036b4fac4
diff --git a/core/binary.mk b/core/binary.mk
index 0c6d8e8..c2e3069 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -1412,8 +1412,7 @@
     # Set up global default checks
     my_tidy_checks := $(WITH_TIDY_CHECKS)
     ifeq ($(my_tidy_checks),)
-      # AOSP source did not follow Google readability rules.
-      my_tidy_checks := -*,google*,-google-readability*
+      my_tidy_checks := $(call default_global_tidy_checks,$(LOCAL_PATH))
     endif
     # Append local clang-tidy checks.
     ifneq ($(LOCAL_TIDY_CHECKS),)