swift234

Reenable -global-opt after teaching it to avoid hoisting initializer calls unless they are inside loops.

<rdar://problem/16792521> Hoist globals initializers out of loops.

Long term, we should recognize hot/cold idioms for ObjC support and
provide an analysis that identifies cold branch targets. However,
identifying loops is trivial and self-contained so more appropriate
for WWDC.

I have not been able to reproduce the StringSort regression. However,
I compared Benchmark.swift with Release build before and after
enabling the pass with this patch and saw no regressions.

Swift SVN r17554