Half-Life: Source HD Pack Sound Patch addon

During the 2013 Steampipe update for Half-Life: Source, the HD pack from Half-Life 1 was added to the game and is a toggle in the options menu. However; there were some problems with the integration that still have not been fixed as of 2018. Some weapon sounds do not work, specifically with the pistol and the assault rifle. This fix/patch (which I did not make and is taken from a github user) fixes those sound problems with the HL:S HD Pack.