Revert r253528: "[X86] Enable shrink-wrapping by default."

This caused PR25607 and also caused Chromium to crash on start-up.

(Also had to update test/CodeGen/X86/avx-splat.ll, which was committed
after shrink wrapping was enabled.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254044 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed