Revert "build: fix configure detection of if_bridge.h on RHEL 6"
Revert "build: fix configure detection of if_bridge.h on RHEL 6"

This reverts commit 2df8d99138dc8396c7d46c3cceca8ce2e93b605a.

The change breaks configure on any recent Fedora platform

elmarco/libvirt,jfehlig/libvirt,andreabolognani/libvirt,zhlcindy/libvirt-1.1.4-maintain,elmarco/libvirt,cbosdo/libvirt,shugaoye/libvirt,zhlcindy/libvirt-1.1.4-maintain,cbosdo/libvirt,VenkatDatta/libvirt,andreabolognani/libvirt,olafhering/libvirt,agx/libvirt,nertpinx/libvirt,zippy2/libvirt,taget/libvirt,libvirt/libvirt,andreabolognani/libvirt,agx/libvirt,nertpinx/libvirt,elmarco/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,jardasgit/libvirt,cbosdo/libvirt,crobinso/libvirt,datto/libvirt,zippy2/libvirt,crobinso/libvirt,crobinso/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,taget/libvirt,datto/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,rlaager/libvirt,cbosdo/libvirt,nertpinx/libvirt,zippy2/libvirt,elmarco/libvirt,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,eskultety/libvirt,agx/libvirt,taget/libvirt,cbosdo/libvirt,datto/libvirt,jfehlig/libvirt,olafhering/libvirt,VenkatDatta/libvirt,zhlcindy/libvirt-1.1.4-maintain,VenkatDatta/libvirt,jfehlig/libvirt,eskultety/libvirt,nertpinx/libvirt,eskultety/libvirt,shugaoye/libvirt,datto/libvirt,taget/libvirt,elmarco/libvirt,olafhering/libvirt,eskultety/libvirt,rlaager/libvirt,fabianfreyer/libvirt,libvirt/libvirt,andreabolognani/libvirt,shugaoye/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,agx/libvirt,andreabolognani/libvirt,zhlcindy/libvirt-1.1.4-maintain,jardasgit/libvirt,jardasgit/libvirt,agx/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,olafhering/libvirt,libvirt/libvirt,rlaager/libvirt,nertpinx/libvirt,jardasgit/libvirt,rlaager/libvirt,eskultety/libvirt,taget/libvirt,datto/libvirt,VenkatDatta/libvirt