Detect musl in config.guess wrapper

[Mikael Vidstedt]

Please review the following change which adds support for detecting the musl C library in the config.guess wrapper. With this change in place there’s no need to explicitly specify —host and/or —build to configure.

http://cr.openjdk.java.net/~mikael/webrevs/portola/musl-config.guess/webrev.00/webrev/ <http://cr.openjdk.java.net/~mikael/webrevs/portola/musl-config.guess/webrev.00/webrev/>

Cheers,
Mikael