i965/fs: Drop the emit(fs_inst) overload.

i965/fs: Drop the emit(fs_inst) overload.

Using this emit function implicitly creates three copies, which
is pointlessly inefficient.

1. Code creates the original instruction.
2. Calling emit(fs_inst) copies it into the function.
3. It then allocates a new fs_inst and copies it into that.

The second could be eliminated by changing the signature to

   fs_inst(const fs_inst &)

but that wouldn't eliminate the third.  Making callers heap allocate the
instruction and call emit(fs_inst *) allows us to just use the original
one, with no extra copies, and isn't much more of a burden.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>