Remove LLVM_NOEXCEPT and replace it with noexcept

Now that we have dropped MSVC 2013, all supported compilers support
noexcept and we can drop this portability macro.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284672 91177308-0d34-0410-b5e6-96231b3b80d8
19 files changed