recovery: Switch to clang

And a few trival fixes to suppress warnings.

Change-Id: I38734b5f4434643e85feab25f4807b46a45d8d65
diff --git a/updater/Android.mk b/updater/Android.mk
index 57f43da..a0ea06f 100644
--- a/updater/Android.mk
+++ b/updater/Android.mk
@@ -17,6 +17,8 @@
 # needed only for OTA packages.)
 LOCAL_MODULE_TAGS := eng
 
+LOCAL_CLANG := true
+
 LOCAL_SRC_FILES := $(updater_src_files)
 
 ifeq ($(TARGET_USERIMAGES_USE_EXT4), true)