Always build xtest with -g3

Helps debugging (gdb, valgrind).

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/Android.mk b/Android.mk
index e23c777..051bfe2 100644
--- a/Android.mk
+++ b/Android.mk
@@ -67,6 +67,7 @@
 LOCAL_CFLAGS += -DUSER_SPACE
 LOCAL_CFLAGS += -DTA_DIR=\"/system/lib/optee_armtz\"
 LOCAL_CFLAGS += -pthread
+LOCAL_CFLAGS += -g3
 
 ## target BUILD_OPTEE_OS is defined in the common ta build
 ## mk file included before, and this BUILD_OPTEE_OS will