Update to 20150425 snapshot to unbreak gcc5 build

src/systems/base/koepac_voice_archive.cc:142:27: error:
narrowing conversion of '255' from 'int' to 'int8_t {aka signed char}' inside { }

0x7e, 0x81, 0x7f, 0x80};
                      ^

Changes: https://github.com/eglaysher/rlvm/compare/589e3d2...373a3db
Reported by: DPorts
MFH: 2015Q2