javacomp-script: Remove support for 'gcj'. * build-aux/javacomp.sh.in: Don't test HAVE_GCJ_C. * m4/javacomp.m4 (gt_JAVACOMP): Don't set HAVE_GCJ_C. Don't test whether $JAVAC is gcj. Don't set CONF_JAVAC to 'gcj -C'. Update comment. (gt_JAVACOMP_DISABLED): Don't set HAVE_GCJ_C.