Revert r234786, it contained a bunch of stuff I did not mean to commit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@234787 91177308-0d34-0410-b5e6-96231b3b80d8

• include/clang/AST/Mangle.h[diff]
• include/clang/Basic/Attr.td[diff]
• include/clang/Basic/DiagnosticSemaKinds.td[diff]
• include/clang/Sema/AttributeList.h[diff]
• lib/AST/ItaniumMangle.cpp[diff]
• lib/AST/MicrosoftMangle.cpp[diff]
• lib/CodeGen/CGException.cpp[diff]
• lib/CodeGen/CGStmt.cpp[diff]
• lib/CodeGen/CodeGenFunction.cpp[diff]
• lib/CodeGen/CodeGenFunction.h[diff]
• lib/Driver/SanitizerArgs.cpp[diff]
• test/CodeGen/exceptions-seh-finally.c[diff]
• test/CodeGen/exceptions-seh-leave.c[diff]
• test/CodeGen/exceptions-seh.c[diff]
• test/CodeGenCXX/exceptions-seh.cpp[diff]
• test/SemaCXX/switch-implicit-fallthrough.cpp[diff]