RFR: 8014231: --with-alsa configuration options don't add include or lib directories to proper flags

[Tim Bell]

Erik:

> The ALSA_LIBS and ALSA_CFLAGS variable were correctly setup in 
> configure, but never got propagated any further. This patch adds them 
> to spec.gmk.in to make them available to make, and to the compilation 
> of libjsoundalsa.
>
> http://cr.openjdk.java.net/~erikj/8014231/webrev.01/

Looks good.  Approved.

Tim