libgui: Add pre-MR2-compatible symbol for setPosition

SurfaceControl::setPosition now takes floats instead of integers as
arguments, which breaks linkability from pre-MR2 blobs. Add a direct
compatibility wrapper, since the values are treated in the same
way.

Change-Id: I293d117b94220258a7dbe354d6c0ee26a0d4314a
Merge "libgui: Add pre-MR2-compatible symbol for setPosition" into lp5.0