A common request has been the ability to compile zlib to require no
other libraries.  This --solo option provides that ability.  The price
is that the gz*, compress*, and uncompress functions are eliminated,
and that the user must provide memory allocation and free routines to
deflate and inflate when initializing.

The DESTDIR should not be encoded into symlinks as it is only a
temporary path.  Further, since we install the symlinks into the
same dir as the files, let's use relative links so that they can
always resolve.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

Also added "-motley" to ZLIB_VERSION in zlib.h, so that versions
in-between 1.2.5.1 and 1.2.5.2 that are pulled down from github
can be identified as such if bugs are reported on them.