Add a new option to indicate we want the code generator to emit code quickly,

Add a new option to indicate we want the code generator to emit code quickly,
not spending tons of time microoptimizing it.  This is useful for an -O0
style of build.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24235 91177308-0d34-0410-b5e6-96231b3b80d8