qmmp: update 0.7.5 -> 0.7.6

Changes since 0.7.5:
 * added libav 10 and ffmpeg 2.2 support;
 * fixed url parsing;
 * fixed freezing on playback resume;
 * fixed random freezing in the mplayer plugin;
 * fixed reset selection of tracks when calling context menu;
 * fixed multimedia keys support under win32.