ape: don't hardcode list of ape library directories in /sys/src/ape/lib/mkfile

this change allows one to drop library directories (like
freetype) into /sys/src/ape/lib/ and have them built without
having to change the mkfile.

sys/src/ape/lib/mkfile

@@ -1,6 +1,6 @@
 </$objtype/mkfile
 
-DIRS=9 ap auth bio bsd bz2 draw fmt l mp net sec utf v z
+DIRS=`{echo */}
 
 none:V:
 	echo mk all, install, installall, clean, or nuke