[9fans] new zlib (1.2.6) support &| build

[Jeff Sickel <jas@corpus-callosum.com>]

While hitting some ape pcc errors while building my arm tree,
I realized that zlib was quite a bit out of date.  The latest
zlib-1.2.6 can be pulled down and installed in

	/sys/src/cmd/gs/zlib

You'll need to remove gzio.c if you didn't do a complete replace,
and then modify the following:

term% pwd
/sys/src/ape/lib/z
term% diffy *
diff /n/dump/2012/0207/sys/src/ape/lib/z/mkfile ./mkfile
11c11,14
< 	gzio.$O\
---
> 	gzclose.$O\
> 	gzlib.$O\
> 	gzread.$O\
> 	gzwrite.$O\
39c42
< CFLAGS=-c
---
> CFLAGS=-c -D_POSIX_SOURCE -D_C99_SNPRINTF_EXTENSION
diff /n/dump/2012/0207/sys/src/ape/lib/z/z.proto ./z.proto
5a6,9
> arm	- sys sys
> 	lib	- sys sys
> 		ape	- sys sys
> 			libz.a	- sys sys



libz.a is a dependency for quite a few other components, so I'll
post something new after more testing.

-jas