There are a few changes in glibc-2.10 that might make your software fail to build with it, please refer to my blog post  if you're not sure what the problem is.
And no I don't usually provide emerge --info with these bugs because they are caused by glibc-2.10!
Created attachment 194665 [details]
You sent a mail one year ago about last riting it, now we have patchage that is an "alsa sequencer gui", qjackctl can do the work too. Please go ahead.