Support arch-specific LOCAL_C_INCLUDES.

Bug: 11654773
Change-Id: I89c7ce7ff8bea15cb81f9cd9b0188b54beed3422
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 42ce742..56e17b0 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -148,12 +148,14 @@
 # arch specific variables
 LOCAL_SRC_FILES_$(TARGET_ARCH):=
 LOCAL_CFLAGS_$(TARGET_ARCH):=
+LOCAL_C_INCLUDES_$(TARGET_ARCH):=
 LOCAL_ASFLAGS_$(TARGET_ARCH):=
 LOCAL_NO_CRT_$(TARGET_ARCH):=
 LOCAL_LDFLAGS_$(TARGET_ARCH):=
 ifdef TARGET_2ND_ARCH
 LOCAL_SRC_FILES_$(TARGET_2ND_ARCH):=
 LOCAL_CFLAGS_$(TARGET_2ND_ARCH):=
+LOCAL_C_INCLUDES_$(TARGET_2ND_ARCH):=
 LOCAL_ASFLAGS_$(TARGET_2ND_ARCH):=
 LOCAL_NO_CRT_$(TARGET_2ND_ARCH):=
 LOCAL_LDFLAGS_$(TARGET_2ND_ARCH):=