Disable building libapplypatch on mac

The sdk_mac on build server fails with the error:
bootable/recovery/applypatch/freecache.cpp:23:10: fatal error: 'sys/statfs.h' file not found

So we will disable libapplypatch on mac.

Test: the library still builds on linux; and check the other host targets in the same cl.
Change-Id: Ie4a30708726e51c810f7ad7f1085d38154076cca