Issue 7678: Added -cflag=ccflags switch.  

This allows arguments to be passed to the C compiler being used to drive linking.

I've also opened issue 7678 for this.  (http://d.puremagic.com/issues/show_bug.cgi?id=7678)

I was prompted to make this patch because of issue 5278 remaining unresolved. (http://d.puremagic.com/issues/show_bug.cgi?id=5278)