Variable auto-init of blocks capturing self after init bugfix

Summary:
Blocks that capture themselves (and escape) after initialization currently codegen wrong because this:

  bool capturedByInit =
      Init && emission.IsEscapingByRef && isCapturedBy(D, Init);

  Address Loc =
      capturedByInit ? emission.Addr : emission.getObjectAddress(*this);

Already adjusts Loc from thr alloca to a GEP. This code:

    if (emission.IsEscapingByRef)
      Loc = emitBlockByrefAddress(Loc, &D, /*follow=*/false);

Was trying to do the same adjustment, and a GEP on a GEP (returning an int) triggers an assertion.

<rdar://problem/47943027>

Reviewers: ahatanak

Subscribers: jkorous, dexonsmith, cfe-commits, rjmccall

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58218

llvm-svn: 354147