Re-land "[WinEH] Add an EH registration and state insertion pass for 32-bit x86"

This reverts commit r236360.

This change exposed a bug in WinEHPrepare by opting win32 code into EH
preparation. We already knew that WinEHPrepare has bugs, and is the
status quo for x64, so I don't think that's a reason to hold off on this
change. I disabled exceptions in the sanitizer tests in r236505 and an
earlier revision.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236508 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -266,6 +266,8 @@ bool AsmPrinter::doInitialization(Module &M) {
   case ExceptionHandling::WinEH:
     switch (MAI->getWinEHEncodingType()) {
     default: llvm_unreachable("unsupported unwinding information encoding");
+    case WinEH::EncodingType::Invalid:
+      break;
     case WinEH::EncodingType::Itanium:
       ES = new Win64Exception(this);
       break;