Layoutlib: Fix FontFamily_Delegate use after unref

FontFamily_Delegate was being reused after the nUnref call. The issue is
fixed by storing the reference to the FontFamily_Delegate directly in
the Typeface_Delegate rather than storing the native pointer.

Change-Id: I0db724a83c4be3d7b64ccba0989cd64129f2a785
2 files changed