[openal] Minor update for 1.18.1 binaries

[Chris Robinson]

Just making a note for anyone interested, I just updated the prebuilt 
binary package for 1.18.1 
<http://openal-soft.org/openal-binaries/openal-soft-1.18.1-bin.zip>. 
There is nothing new and nothing removed, and there is no functional 
difference. Everything is even the same build, I simply ran strip on the 
DLLs and executables to remove errant debug info and reduce the file 
sizes (something I thought cmake automatically did for Release builds, 
but I guess not). As a result, both 32-bit and 64-bit versions of 
soft_oal.dll are about 60% of their original size, and the entire 
archive has shaved a few MB off.

If the size never bothered you, there's nothing to concern yourself 
with. But if you noticed the archive being updated, that's why.