[ms-cxxabi] Thread GlobalDecls through to CodeGenModule::getFunctionLinkage.

This is so that we can give destructor variants different linkage later.

Differential Revision: http://llvm-reviews.chandlerc.com/D819

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@183324 91177308-0d34-0410-b5e6-96231b3b80d8
When the template specialization header is missing, set a valid source location for the template keyword when recovering.

Otherwise ClassTemplateSpecializationDecl::getSourceRange() will mistakenly consider itself as an implicit partial specialization
and lead to a crash.

Fixes rdar://14063074

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@183325 91177308-0d34-0410-b5e6-96231b3b80d8