Allow devices to extend the system manifest.

Introduces DEVICE_FRAMEWORK_MANIFEST_FILE, a list
of files which are added to system/manifest.xml.
This is required for devices to properly display
what hals they implement and also therefore for
them to pass vts_treble_vintf_test since it
now tests manifests based on hal origin.

Notice, this is named singularly to match
DEVICE_MANIFEST_FILE which is also a list of files.
They may be better both named "FILES", but for
consistency and legacy reasons, they can be thought
of as "everything that composes the X manifest
file".

Fixes: 70042049
Test: add system manifest extension which needs it
  and it no longer fails vts_treble_vintf_test for
  hals being served from the wrong partitions.

Change-Id: I1f59d5c3cadb7a7d4576b73196ca7b41103a49c5
diff --git a/core/config.mk b/core/config.mk
index dc2b16a..50c2baa 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -816,7 +816,12 @@
   DEFAULT_SYSTEM_DEV_CERTIFICATE := build/target/product/security/testkey
 endif
 
-FRAMEWORK_MANIFEST_FILE := system/libhidl/manifest.xml
+FRAMEWORK_MANIFEST_INPUT_FILES := system/libhidl/manifest.xml
+ifdef DEVICE_FRAMEWORK_MANIFEST_FILE
+  FRAMEWORK_MANIFEST_INPUT_FILES += $(DEVICE_FRAMEWORK_MANIFEST_FILE)
+endif
+$(.KATI_obsolete_var DEVICE_FRAMEWORK_MANIFEST_FILE,No one should ever need to use this.)
+
 FRAMEWORK_COMPATIBILITY_MATRIX_FILES := $(wildcard hardware/interfaces/compatibility_matrix.*.xml)
 
 BUILD_NUMBER_FROM_FILE := $$(cat $(OUT_DIR)/build_number.txt)