Fix nanomsg-specific EPROTO value conflict

If a platform is missing a POSIX errno that nanomsg requires, nanomsg will
provide its own definition.  The definitions of EAFNOSUPPORT and EPROTO
erroneously resolved to the same value.

This patch cranks EPROTO up to 11.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Evan Wies added to AUTHORS file

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>