Ubuntu Apport-Bug – Equivalent in Fedora or Mint?

OpenSuse Build Service perhaps? Don't let the name OpenSuse fool you, it supports other distros as well. I don't believe it gives you a yum repository, but it does give you a place for users to download your .rpm files. But the coolest thing it does is it will compile your package for you in whatever architectures and whatever versions of Fedora/Suse/etc you want to support.

Main page: https://build.opensuse.org/
Wiki page: http://en.opensuse.org//openSUSE:Build_Service

The Fedora PkgDB does have a search syntax so you could search for builds with /usr/bin/g++ in it by searching for file:/usr/bin/g++ and click Builds. Click on the blue (i) for more details. The GCC package has several sub-packages, as described in the gcc.spec file you showed above, which has added to the confusion.