Move get_my_path_darwin to C++.

As long as we have C in here, we can't use C++ in our headers.

Change-Id: Ibccaa77a5af506dc504aa9c39c8dca5dcdbeccab
diff --git a/adb/Android.mk b/adb/Android.mk
index 3733ae3..8a99e6b 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -34,7 +34,7 @@
 
 LIBADB_darwin_SRC_FILES := \
     fdevent.cpp \
-    get_my_path_darwin.c \
+    get_my_path_darwin.cpp \
     usb_osx.c \
 
 LIBADB_linux_SRC_FILES := \
diff --git a/adb/get_my_path_darwin.c b/adb/get_my_path_darwin.cpp
similarity index 100%
rename from adb/get_my_path_darwin.c
rename to adb/get_my_path_darwin.cpp