Some minor updates

Hi :)

I've made some more minor updates. Please have a look at it.

First:
I've changed the "eerror" to "ewarn". This is mostly a personal opinion. I think the message should only warn the user about the problem with the useflag. eerror on the other hand comes mostly in pair with "die" and thus cancels to install usually. If you look with "qgrep eerror -A 1" you see many ebuild's die after eerror - anyway it's up to you about that change :)

Secondly:
I've also rewrote the configure part in the live ebuild. I wasn't completely happy with my actual solution even though it looked quite simple. A problem with the actual solution was that on the non-native arch (32bit) jack/pulseaudio and debug won't be disabled explicitly (but also not enabled), actually nothing would be passed. Even though it's rather a non-issue, it's still not correct.
A solution would be:
```
$(multilib_is_native_abi && use_enable jack || echo "--disable-jack" ) 
```
However, after talking to gentoo devs (about another ebuild) i was said that this wasn't perfectly nice.

I fixed that now - it's a bit more text now, but it should be correct.

On a side note: 
multilib_is_native_abi and multilib_build_binaries is basically the same. Gentoo devs however decided to ditch multilib_is_native_abi (it still works but shouldn't be used anymore) in favor of multilib_build_binaries. I can't recall the exact reason, but i know multilib_build_binaries is superior ;)