ports-mgmt/synth: Upgrade version 1.10 => 1.11

This fixes a regression in building ports that have dependences that
install kernel modules. When DTrace support was added by providing a
read-only mount of /boot to the builder, the kernel modules could no
longer be installed at /boot/modules by pkg(8).

Previously, although successful, module installs would have caused a file
system violation on test mode checks. Since /boot is now excluded from
checks (since DTrace support), leftovers in /boot/modules will not be
detected in test mode. The fix is too elaborate and FreeBSD-specific
to worry about (plus there's the philosophy question about why the ports
framework is even allowed to modify the base but that's out of scope).