Remove build and runtime dependencies on e2fsprogs and e2fsprogs-devel.
Add support for --with/--without libsodium and --with/--without pgm
command line options.
Require pkg-config, use pkg-config to pull seek libsodium.
Correct declaration of HAVE_LIBSODIUM.
Append to libzmq_la_CPPFLAGS and libzmq_la_LIBADD.
Support both --with-* and --without-* options for libsodium and pgm
Merge pull request #3 from johntconklin/master

Cherry-picked configure and rpmbuild fixes from libzmq/master