Add dependencies for files in LOCAL_PROGUARD_FLAGS

Do this by introducing a new LOCAL_PROGUARD_FLAGS_DEPS variable that we
can modify anytime we add a file reference to LOCAL_PROGUARD_FLAGS.

An alternative would have been to switch to LOCAL_PROGUARD_FLAG_FILES,
but that would have been much harder to ensure the same command line
ordering.

Bug: 130111713
Test: treehugger
Change-Id: If367197b30d563e0796f0cafa00be1f275f2c406
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 3cc8594..2e24eb9 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -221,6 +221,7 @@
 LOCAL_PROGUARD_ENABLED:=
 LOCAL_PROGUARD_FLAG_FILES:=
 LOCAL_PROGUARD_FLAGS:=
+LOCAL_PROGUARD_FLAGS_DEPS:=
 LOCAL_PROPRIETARY_MODULE:=
 LOCAL_PROTOC_FLAGS:=
 # lite(default),micro,nano,stream,full,nanopb-c,nanopb-c-enable_malloc,nanopb-c-16bit,nanopb-c-enable_malloc-16bit,nanopb-c-32bit,nanopb-c-enable_malloc-32bit