Log Message:
clang: enable __float128 on netbsd/x86

While it is debatable whether we want to have this definition upstream,
this is very necessary in the package for the purpose of building
www/firefox once it is updated to 63.0.

This is because netbsd's base libstdc++ has some __float128 in headers
and otherwise we get fatal errors in clang builds, or in firefox's case,
when generating bindings for Rust via clang.

PR toolchain/53679
Bump PKGREVISION.