Move usb_osx to C++.

Change-Id: I21673211a702cc4f31d4311c36e2a4b22e55fac8
diff --git a/adb/Android.mk b/adb/Android.mk
index c27b4af..133a7c4 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -35,7 +35,7 @@
 LIBADB_darwin_SRC_FILES := \
     fdevent.cpp \
     get_my_path_darwin.cpp \
-    usb_osx.c \
+    usb_osx.cpp \
 
 LIBADB_linux_SRC_FILES := \
     fdevent.cpp \