display: makefile fixes

* Deprecate LOCAL_COPY_HEADERS on newer builds
* Use a display header export path instead
* Consolidate cflags

CRs-Fixed: 2023356
Change-Id: Ibb8900a77fc3fa47e6e54cd1649503eba12de8cd
diff --git a/libgralloc1/Android.mk b/libgralloc1/Android.mk
index fb8c74a..6bbbda4 100644
--- a/libgralloc1/Android.mk
+++ b/libgralloc1/Android.mk
@@ -9,6 +9,7 @@
 LOCAL_C_INCLUDES              := $(common_includes) \
                                  external/libcxx/include/
 
+LOCAL_HEADER_LIBRARIES        := display_headers
 LOCAL_SHARED_LIBRARIES        := $(common_libs) libqdMetaData libsync libqdutils
 ifneq ($(TARGET_IS_HEADLESS), true)
 LOCAL_SHARED_LIBRARIES        += libdrmutils