RFR: Handle confstr version lookup failures gracefully

[Mikael Vidstedt]

During bootstrapping, os::Linux::libpthread_init() tries to discover the versions of (g)libc and libpthread respectively. This is done using confstr(3). However, musl doesn’t implement support for version discovery, so confstr will return 0/EINVAL.

This change makes the code handle confstr failures gracefully, and defaults using the string “unknown” if the version information cannot be looked up.

http://cr.openjdk.java.net/~mikael/webrevs/portola/glibcversion/webrev.01/hotspot/webrev/

Cheers,
Mikael