package/fetchmail: Fix checking for statically build OpenSSL with libz dependency

package/fetchmail: Fix checking for statically build OpenSSL with libz dependency

Fixes
http://autobuild.buildroot.net/results/48a/48ad6d3659cf1f04581b7e3d115bebf454ff17fd/

To fix the error add "-lz" to LIBS variable and re-order the libraries in
configure.ac. Please note line 797 in configure.ac:
dnl XXX FIXME: use pkg-config if available!

Quote of the compile error:

configure: Enabling OpenSSL support in /home/br/br/output/host/usr/i486-buildroot-linux-uclibc/sysroot/usr.
checking for additional library dependencies of SSL... error
configure: error: cannot link with SSL - check config.log

In config.log multiple linking errors to libz can be found:

configure:10099: /home/br/br/output/host/usr/bin/i486-ctng-linux-uclibc-gcc -o
  conftest -D_LARGEFILE_SOURCE -D_LARGEFILE64
  /home/br/br/output/host/usr/i486-buildroot-linux-uclibc/sysroot/usr/lib/libcrypto.a(c_zlib.o):
  In function `zlib_stateful_c_zlib.c:(.text+0x56): undefined reference to `inflate'

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>