CodeGen:  Move check of EnablePostRAScheduler to avoid disabling antidependency breaker
CodeGen:  Move check of EnablePostRAScheduler to avoid disabling antidependency breaker

Previously, specifying -post-RA-scheduler=true had the side effect of
disabling the antidependency breaker, yielding different behavior than
if the post-RA-scheduler was enabled via the scheduling model.

Differential Revision: http://reviews.llvm.org/D20186


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@270077 91177308-0d34-0410-b5e6-96231b3b80d8

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