Allow 'static' storage specifier on an out-of-line member function template

declaration in MSVCCompat mode

Microsoft compiler permits the use of 'static' storage specifier outside
of a class definition if it's on an out-of-line member function template
declaration.

This patch allows 'static' storage specifier on an out-of-line member
function template declaration with a warning in Clang (To be compatible
with Microsoft).

Intel C/C++ compiler allows the 'static' keyword with a warning in
Microsoft mode. GCC allows this with -fpermissive.

Patch By: Manna

Differential Revision: https://reviews.llvm.org/D56473

Change-Id: I97b2d9e9d57cecbcd545d17e2523142a85ca2702

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@352219 91177308-0d34-0410-b5e6-96231b3b80d8