Support -fno-delayed-template-parsing in clang-cl.exe

Summary:
This change adds support for the -fno-delayed-template-parsing option in
clang-cl.exe. This allows developers using clang-cl.exe to opt out of
emulation of MSVC's non-conformant template instantiation implementation
while continuing to use clang-cl.exe for its emulation of cl.exe
command-line options. The default behavior of clang-cl.exe
(-fdelayed-template-parsing) is unchanged.

The MSVC Standard Library implementation uses clang-cl.exe with this
switch in its tests to ensure that the library headers work on compilers
with the conformant two-phase-lookup behavior.

Reviewers: majnemer, cfe-commits, DaveBartolomeo

Differential Revision: https://reviews.llvm.org/D22275

llvm-svn: 290990