Fix Mac build.

Prior to https://android-review.googlesource.com/#/c/134253/ the
makefile had assumed !Windows was the same as Linux, so the Mac was
actually getting all the Linux sources as well. I mistakenly didn't
add fdevent.cpp to the Darwin sources in that change.

Change-Id: I4e12a394e9a2baf7c1e3c711a01a6b5fccbf79d9
diff --git a/adb/Android.mk b/adb/Android.mk
index 2656268..327591f 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -28,7 +28,7 @@
     -D_XOPEN_SOURCE -D_GNU_SOURCE \
     -fvisibility=hidden \
 
-LIBADB_darwin_SRC_FILES := get_my_path_darwin.c usb_osx.c
+LIBADB_darwin_SRC_FILES := fdevent.cpp get_my_path_darwin.c usb_osx.c
 LIBADB_linux_SRC_FILES := fdevent.cpp get_my_path_linux.c usb_linux.c
 LIBADB_windows_SRC_FILES := get_my_path_windows.c sysdeps_win32.c usb_windows.c