recovery: Switch to clang

And a few trival fixes to suppress warnings.

Change-Id: I38734b5f4434643e85feab25f4807b46a45d8d65
diff --git a/tests/Android.mk b/tests/Android.mk
index 02a272a..4ce00b4 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -17,6 +17,7 @@
 LOCAL_PATH := $(call my-dir)
 
 include $(CLEAR_VARS)
+LOCAL_CLANG := true
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_STATIC_LIBRARIES := libverifier
 LOCAL_SRC_FILES := asn1_decoder_test.cpp