gallium/gallivm: code generation options for LLVM 3.1+

gallium/gallivm: code generation options for LLVM 3.1+

LLVM 3.1+ haven't more "extern unsigned llvm::StackAlignmentOverride"
and friends for configuring code generation options, like stack
alignment.

So I restrict assiging of lvm::StackAlignmentOverride and other
variables to LLVM 3.0 only, and wrote similiar code using
TargetOptions.

This patch fix segfaulting of WINE using llvmpipe built with LLVM 3.1

Signed-off-by: Alexander V. Nikolaev <avn@daemon.hole.ru>
Signed-off-by: José Fonseca <jose.r.fonseca@gmail.com>