libstrophe: 0.9.1 -> 0.9.2

Semi-automatic update. These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 0.9.2 with grep in /nix/store/gc20iqfsfjj6c9ikgz06k3rk3597h22q-libstrophe-0.9.2
- found 0.9.2 in filename of file in /nix/store/gc20iqfsfjj6c9ikgz06k3rk3597h22q-libstrophe-0.9.2