arc should use configure.cc

[ryandesign (Ryan Carsten Schmidt)]

$ port install arc
--->  Fetching arc
--->  Attempting to fetch arc-5.21o.tgz from http://leopard.local/distfiles/arc
--->  Attempting to fetch arc-5.21o.tgz from http://superb-west.dl.sourceforge.net/arc
--->  Verifying checksum(s) for arc
--->  Extracting arc
--->  Applying patches to arc
--->  Configuring arc
--->  Building arc
Error: Target org.macports.build returned: shell command " cd "/mp/var/macports/build/_Users_rschmidt_macports_dports_archivers_arc/work/arc-5.21o" && nice -n 10 make all OPT="-O2" " returned error 2
Command output: gcc -O2 -DBSD=1 -c arc.c
gcc -O2 -DBSD=1 -c arc.c
gcc: Error: You should be using ${configure.cc}
See http://trac.macports.org/wiki/UsingTheRightCompiler
make: *** [arc.o] Error 1

A patch is attached which fixes this issue. If there is no objection, I'm happy to commit it.

[ryandesign (Ryan Carsten Schmidt)]

Fixed in r68754.