Android.mk : Fix compilation for build outside of source

Trying to specify Android build location outside of souce directory's
default 'out' using OUT_DIR_COMMON_BASE env variable, results in the
following error
"....
build/core/binary.mk:1480: error: external/optee_test/Android.mk:
xtest: C_INCLUDES must be under the source or output directories:
"
Fix the error by moving host_include/ from LOCAL_C_INCLUDES to LOCAL_CFLAGS

Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Tested-by: Victor Chong <victor.chong@linaro.org> (hikey620)
Acked-by: Victor Chong <victor.chong@linaro.org>
[jf: wrap commit text]
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
diff --git a/Android.mk b/Android.mk
index 086f500..e371cf8 100644
--- a/Android.mk
+++ b/Android.mk
@@ -78,7 +78,6 @@
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/host/xtest \
 		$(LOCAL_PATH)/host/xtest/adbg/include\
 		$(LOCAL_PATH)/host/xtest/xml/include \
-		$(TA_DEV_KIT_DIR)/host_include \
 		$(LOCAL_PATH)/ta/concurrent/include \
 		$(LOCAL_PATH)/ta/concurrent_large/include \
 		$(LOCAL_PATH)/ta/create_fail_test/include \
@@ -95,7 +94,7 @@
 		$(LOCAL_PATH)/ta/sdp_basic/include
 
 # Include configuration file generated by OP-TEE OS (CFG_* macros)
-LOCAL_CFLAGS += -include conf.h
+LOCAL_CFLAGS += -I $(TA_DEV_KIT_DIR)/host_include -include conf.h
 LOCAL_CFLAGS += -pthread
 LOCAL_CFLAGS += -g3
 LOCAL_CFLAGS += -Wno-missing-field-initializers -Wno-format-zero-length