gnuregex: fix for Leopard ppc

[barracuda156]

I cannot modify someone else’s ticket, so opening a new one. gnuregex builds for ppc (Leopard and Snow Leopard) with this change to its portfile:

post-build {
    set command "libtool -lSystem -ldylib1.10.5.o -dynamic -install_name ${prefix}/lib/libgnuregex.dylib -o libgnuregex.dylib regex.o"
    ui_debug "$command"
    system "cd ${worksrcpath} && ${command}"
}

In particular, -ldylib1.10.5.o is to be added. Discussion here: ​https://trac.macports.org/ticket/52466

16. S. I can check on Tiger whether -ldylib1.10.4.o works later on.