Some hangs are fooling the postmortem dump code into
running off the end of a buffer. Fix this by making
its bounds check logic work better by reusing the
logic from kgsl_find_region().
Userspace will set a flag in the context if preambles are in use. If
they are, we can safely skip save and restore commands for the
context. GMEM save/restore is still required. To improve performance,
preamble commands are skipped when the context hasn't changed since
the last issueibcmds.
from Code Aurora
