[OPENMP] Fix for http://llvm.org/PR25142: openmp: Assertion failed: DD &&...

[OPENMP] Fix for http://llvm.org/PR25142: openmp: Assertion failed: DD && "queried property of class with no definition", file AST/DeclCXX.h
Added processing for template specialization during data-sharing attributes analysis

llvm-svn: 255879