zlib: Update to 1.2.11

zlib: Update to 1.2.11

Based on:
http://git.ipfire.org/?p=people/mlorenz/ipfire-2.x.git;a=commit;h=b693162e9fdc7c4cae2f148e8c7832c689ac6fd2
http://git.ipfire.org/?p=people/mlorenz/ipfire-2.x.git;a=commit;h=43a3b9986b7710eb685f00d6099965ebb220c012

Sadly, I couldn't avoid this configure-error while building 'clamav':

...
checking for zlib installation... using /usr
configure: error: The installed zlib version may contain a security bug.
Please upgrade to 1.2.2 or later: http://www.zlib.net.
You can omit this check with --disable-zlib-vcheck but DO NOT REPORT any stability issues then!
...

'clamav' seems to check 'zlib.h' for an appropriate zlib version ('clamav'-configure,
line 18679ff) greater v1.2.1 (line 18719ff), but I didn't find a solution for 1.2.11.

Therefore, '--disable-zlib-vcheck' was added to 'clamav'-configure options.
Any hints are welcome.

Testing zlib 1.2.11 with clamav 0.96.2 didn't find any seen problems so far.

Best,
Matthias

Signed-off-by: Matthias Fischer <matthias.fischer@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>