Lavapipe support on Fuchsia.

This primarily involves adding files corresponding to the
existing files.  However, some other changes were needed,
most notably providing LLVM with a custom memory mapper which is able
to mark allocated pages as executable (Fuchsia does this differently
than other platforms).

Reviewed-by: John Rosasco <>

[lavapipe] Fix build error, missing input

Change-Id: I8870024328c59072c945e79d672dd17a2e4b3797
Reviewed-by: John Bauman <>
Commit-Queue: John Rosasco <>
24 files changed