Invalidate the instruction cache right before we start actually executing code, otherwise
we can miss some that came later. This is still not quite right for a truly lazilly
compiled environment, but it's closer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162803 91177308-0d34-0410-b5e6-96231b3b80d8