[clang-tidy] Fix a false positive in the make_pair checker if an argument has a explicit template argument.

This required a rather ugly workaround for a problem in ASTMatchers where
callee() is only overloaded for Stmt and Decl but not for Expr.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@213509 91177308-0d34-0410-b5e6-96231b3b80d8