this fixes virtualbox not compiling with distcc

https://bugs.gentoo.org/show_bug.cgi?id=351979
http://code.google.com/p/distcc/issues/detail?id=83
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=626926

--- distcc-3.1.orig/source/src/arg.c
+++ distcc-3.1/source/src/arg.c
@@ -515,6 +515,8 @@
             }
             free(argv);
             *argv_ptr = argv = new_argv;
+            i += extra_args - 1;
+            argc += extra_args - 1;
         }
     }
     return 0;