Add a configure check for zlib (Ryota OZAKI).

This patch makes configure check zlib devel files installed.
Current configure doesn't check that, so make will fail if they
are not installed.

Signed-off-by: Ryota Ozaki <ozaki.ryota@gmail.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5456 c046a42c-6fe2-441c-8c8c-71466251a162
