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

[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.

llvm-svn: 213509