www/fabio: Update 1.6.4 => 1.6.11, fix runtime

A recent update to Consul causes Fabio to fail to register itself in the
service directory. Consul has apparently become stricter in its
interpretation of IPv4 addresses and fails to recognize an IPv4 address
surrounded by square brackets. Versions prior to 1.22 permitted this.
Fabio (prior to 1.6.11) sends its IPv4 address wrapped in square
brackets and will fail to register on a newer Consul.

Changelog:
https://github.com/fabiolb/fabio/blob/master/CHANGELOG.md#v1611-2025-12-09

While here replace PORTVERSION with DISTVERSION.

PR: 294048
Approved by: blanket (fix runtime)
Sponsored by: UNIS Labs
MFH: 2026Q1