recovery: Switch to clang

And a few trival fixes to suppress warnings.

Change-Id: I38734b5f4434643e85feab25f4807b46a45d8d65
diff --git a/minadbd/Android.mk b/minadbd/Android.mk
index a7a3e08..3db3b41 100644
--- a/minadbd/Android.mk
+++ b/minadbd/Android.mk
@@ -15,6 +15,7 @@
     fuse_adb_provider.cpp \
     services.cpp \
 
+LOCAL_CLANG := true
 LOCAL_MODULE := libminadbd
 LOCAL_CFLAGS := $(minadbd_cflags)
 LOCAL_CONLY_FLAGS := -Wimplicit-function-declaration