Moving zlib so that others may use it

[Corey Minyard <minyard@acm.org>]

I'm working on a function that uses zlib in the kernel, and I know of 
other places zlib is used (ppp_deflate, jffs2, mcore).  I would expect 
more users to come along.

I would like to propose putting zlib in the lib directory and making it 
optionally compile if it is needed.  It's pretty easy to move the files 
around and make a few small changes to the code.  However, how do I 
configure such a thing?  I could add something like:

   if [ "$CONFIG_PPP_DEFLATE" = "y" ]; then
      define_tristate CONFIG_ZLIB y
   fi
   if [ "$CONFIG_PPP_DEFLATE" = "m" ]; then
      if [ "$CONFIG_ZLIB" != "y" ]; then
         define_tristate CONFIG_ZLIB m
      fi
   fi

to every place that uses it, or I could put something like:

   if [ "$CONFIG_JFFS2_FS" = "y" \
        -o "$CONFIG_PPP_DEFLATE" = "y" ]; then
      define_tristate CONFIG_ZLIB y
   else
      if [ "$CONFIG_JFFS2_FS" = "m" \
          -o "$CONFIG_PPP_DEFLATE" = "m" ]; then
         define_tristate CONFIG_ZLIB m
      fi
   fi

at the end of the config.  I would prefer the latter, but there is not 
an "end of config" place, you would have to put it at the end of every 
config.in (about 15 architectures right now).  I propose to add a 
Config.in to the lib directory that is sourced at the end of every 
config.in for the architectures.  I'll do the work if it's willing to be 
accepted into the kernel.

-Corey