Update ruby193-rubygem-passenger to 4.0.18-9.4.el6

- Keep passenger_native_support in native/ dir for RHSCL compatibility
- Fix extdir on Ruby 1.8 (dcleal@redhat.com)
- Replace native library loading patch, force rubygems to add 'exts' to load
- Fix ruby_libdir for Ruby 1.8 builds (dcleal@redhat.com)
Update rubygem-passenger to 4.0.18-9.4.el6

- Keep passenger_native_support in native/ dir for RHSCL compatibility
- Fix extdir on Ruby 1.8 (dcleal@redhat.com)
- Replace native library loading patch, force rubygems to add 'exts' to load
- Fix ruby_libdir for Ruby 1.8 builds (dcleal@redhat.com)