Update support for Solaris.

Adds support for the latest TAP driver from
http://www.whiteboard.ne.jp/~admin2/tuntap/, so tinc now also works in switch
mode on Solaris 11.

Conflicts:
	src/solaris/device.c
Include <limits.h> for PATH_MAX.
Stricter check for raw socket support.
Use hardcoded value for TUNNEWPPA if net/if_tun.h is missing on Solaris.

Conflicts:
	src/solaris/device.c
Fix incorrectly merged bits from 80cd2ff73071941a5356555b85a00ee90dfd0e16.
Don't enable -fstack-protector-all.

It is not supported on all architectures and is problematic on some
platforms.