hwc: Add support for external-only layers

Add support for different types of external-only layers
EXTERNAL_ONLY: General purpose
EXTERNAL_BLOCK: Blocks the display of other ext-only layers
EXTERNAL_CC: Used for closed captions with videos.

Change-Id: I9cc7b9a1dbf1085194725474d6a4d1094e27a0c8
Acked-by: Saurabh Shah <saurshah@codeaurora.org>
diff --git a/libhwcomposer/Android.mk b/libhwcomposer/Android.mk
index 05d033e..51f1e00 100644
--- a/libhwcomposer/Android.mk
+++ b/libhwcomposer/Android.mk
@@ -9,8 +9,14 @@
                                  libqdutils libhardware_legacy libdl libmemalloc
 LOCAL_CFLAGS                  := $(common_flags) -DLOG_TAG=\"hwcomposer\"
 LOCAL_ADDITIONAL_DEPENDENCIES := $(common_deps)
-LOCAL_SRC_FILES               :=  hwc.cpp hwc_video.cpp hwc_utils.cpp \
-                                  hwc_uimirror.cpp hwc_external.cpp \
-                                  hwc_uevents.cpp hwc_copybit.cpp \
-                                  hwc_mdpcomp.cpp
+LOCAL_SRC_FILES               := hwc.cpp          \
+                                 hwc_video.cpp    \
+                                 hwc_utils.cpp    \
+                                 hwc_uimirror.cpp \
+                                 hwc_external.cpp \
+                                 hwc_uevents.cpp  \
+                                 hwc_copybit.cpp  \
+                                 hwc_mdpcomp.cpp  \
+                                 hwc_extonly.cpp
+
 include $(BUILD_SHARED_LIBRARY)