[Allocator] MSVC apparantly has broken SFINAE context handling of
'sizeof(T)' for T == void and produces a hard error. I cannot fathom why
this is OK. Oh well. switch to an explicit test for being the
(potentially qualified) void type, which is the only specific case I was
worried about. Hopefully this survives the libstdc++ build bots which
have limited type traits implementations...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206256 91177308-0d34-0410-b5e6-96231b3b80d8
Fix broken build of llvm using clang.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206257 91177308-0d34-0410-b5e6-96231b3b80d8
[Allocator] Fix r206256 which got the enabling case backwards on these
overloads. This doesn't matter *that* much yet, but it will in
a subsequent patch. I had tested the original pattern, but not my
attempt to pacify MSVC. This at least appears to work. Still fixing the
rest of the fallout in the final patch that uses these overloads, but it
will follow shortly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206259 91177308-0d34-0410-b5e6-96231b3b80d8
X86JITInfo: [x86] Rework r206240, X86CompilationCallback_SSE() should be called for SSE-enabled code generator, even if LLVM is not built with -msse.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206261 91177308-0d34-0410-b5e6-96231b3b80d8