zdeflate and zinflate
---------------------
The zdeflate utility creates a compressed file using the zlib stream
interface. Syntax:

  zdeflate <infile> <outfile>

To build, bung through CC linking to stubs and zlib only.

The zinflate utility does the same thing, only backwards.

minigzip
--------
To build the example minigzip

  cc -DRISCOS -c minigzip.c
  link -aif -o minigzip minigzip.o C:zlib.o.zlib C:o.stubs

To test it

  md5         mytest             <-- note this value
  minigzip -f mytest
  minigzip -d mytest-gz
  md5         mytest             <-- is it the same?

and again for the other compression options

  minigzip -h mytest
  minigzip -9 mytest

Then to use the SWIs instead of linking against zlib directly

  amu COMPONENT=zlibmodlib
  cc -DRISCOS -c minigzip.c
  link -aif -o minigzip minigzip.o zlibmodlib.o C:o.stubs

TestGZSWIs
----------
This tests the basic usage of ZLib_GZ* SWIs, including the RISC OS
extension modifier 'R' to preserve load/exec addresses in the header.
