This was added in the upgrade to C++17. It's no longer needed since
fixing Clang compatibility got rid of non-conforming templates.
It's no longer needed and getting rid of it is a (minor) quality of
life enhancement since it gets rid of a spurious error when using
Clang based build tools (language server, etc.) while compiling with
GCC.
Signed-off-by: Adam C. Emerson <aemerson@redhat.com>