hayabusa: removed empty gsm.mk

https://github.com/CyanogenMod/android_vendor_cm/commit/0160f873c4a65a4276f11d88c4c96df50fd26d50

Change-Id: I1fe21ce867bcc86b5c076e1a3dbf7564597c5e2a
hayabusa: enable multi-user support

Change-Id: I507b795654a120b648c458242ea76723df788e6f