find zlib and OpenSSL using pkg-config / PKG_CHECK_MODULES from pkg.m4

looking for a static list of lib folders in the multi-arch age is
wrong and broken, as it won't find the proper lib in (e.g.)
/usr/lib/x86_64-linux-gnu/ and maybe the wrong one in /usr/lib/.
remove check_ssl.m4 and check_zlib.m4, they are not needed anymore
remove unneeded m4 files, the macros in there are unused
libcrypto is actually enough

this also solves funny --as-needed ordering issues on (at least)
Ubuntu 12.04
link the lib with its dependencies, not the resulting binary
Merge pull request #10 from evgeni/autofoo-cleanup

Use pkg-config to find zlib and OpenSSL. Thanks for the pull request!