Merge llvm, clang, lld, lldb, compiler-rt and libc++ release_70 branchr339999, resolve conflicts, and bump version numbers.PR: 230240,230355
Update generated config headers, and version numbers.
Merge llvm, clang, lld, lldb, compiler-rt and libc++ r304659, and updatebuild glue.
Merge llvm, clang, lld, lldb, compiler-rt and libc++ r302069, and updatebuild glue (preliminary, not all option combinations work yet).
For lldb, delete the custom Xcode-only Host/Config.h, and provide apre-generated version in lib/clang/include/lldb/Host instead, similar towhat we do for clang, llvm and lld.
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