Revert r129235 pending a vetting of the EH rewrite.

Revert r129235 pending a vetting of the EH rewrite.
--- Reverse-merging r129235 into '.':
D    test/Feature/bb_attrs.ll
U    include/llvm/BasicBlock.h
U    include/llvm/Bitcode/LLVMBitCodes.h
U    lib/VMCore/AsmWriter.cpp
U    lib/VMCore/BasicBlock.cpp
U    lib/AsmParser/LLParser.cpp
U    lib/AsmParser/LLLexer.cpp
U    lib/AsmParser/LLToken.h
U    lib/Bitcode/Reader/BitcodeReader.cpp
U    lib/Bitcode/Writer/BitcodeWriter.cpp

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129259 91177308-0d34-0410-b5e6-96231b3b80d8