omap4xxx: Locate kernel headers

omap4xxx comes with a set of needed kernel headers - but without
the right compiler flags to find them.

Change-Id: I2dba67cfc4c752e79011c270519c0cbe48b94ea8
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
diff --git a/hwc/Android.mk b/hwc/Android.mk
index c6a2eae..50603a6 100644
--- a/hwc/Android.mk
+++ b/hwc/Android.mk
@@ -14,7 +14,7 @@
 LOCAL_MODULE_TAGS := optional
 
 LOCAL_MODULE := hwcomposer.omap4
-LOCAL_CFLAGS := -DLOG_TAG=\"ti_hwc\"
+LOCAL_CFLAGS := -DLOG_TAG=\"ti_hwc\" -I$(LOCAL_PATH)/../kernel-headers
 LOCAL_C_INCLUDES += external/libpng external/zlib
 # LOG_NDEBUG=0 means verbose logging enabled
 # LOCAL_CFLAGS += -DLOG_NDEBUG=0