i965: Move more code into codegen-branch of the fs_visitor::run() if statement

i965: Move more code into codegen-branch of the fs_visitor::run() if statement

These last few operations all only apply when we've actually generated
code, optimized and allocated registers.  The dummy and the repclear
shaders don't need the gen4 send workaround, and don't spill.  This
means we can move these lines into the else-branch, which will make
the following refactoring easier.

v2 (Ken): Rebase on master, which removed the uncompressed stack.

Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>