Not entirely sure if it's breakage related to the necessary defines listed in the reference URL, or just the fact the configure script freaks out at the roll over from 0.9 to 1.0 and uses 0.5. Either way, it's broke, patch to follow shortly.
Created attachment 24261 [details, diff] patch to fix compilation/configuring A couple of things- This corrects configure.ac, and configure. You'll need to touch configure in the ebuild, since even if the patch was ordered to work on configure.ac then configure, it's possible it'll try to regenerate it's configure script. Either way, configuration is fixed, and reports it as 0.9 (which the API is pretty much). From there, patch the 0.9 alsa-lib file to add necessary definitions- that may not be needed, didn't check (likely is, see URL).
touching configure.ac w/out running the autotools could easily lead to pissed off timestamps ... best to just patch configure and send the rest upstream ;)
Touching configure.ac _would_ trigger autotools leading to autohell (TM). *shudder* Touching configure ought to handle it; both files are patched- so configure.ac modifications ought to be sent upstream, along w/ the alsa 0.9.x specific c file modifications. Meanwhile the patch fixes configure, so we're covered as long as it's touched.
tested and added to cvs, thanks for the patch