pkg/60131: Disable libdrm for packages by default on macOS

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>Number:         60131
>Category:       pkg
>Synopsis:       Disable libdrm for packages by default on macOS
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 25 19:00:00 +0000 2026
>Originator:     Daniel
>Release:        trunk (commit 0a59679e7d0d979d67ea641d1b753820f1e4e149)
>Organization:
>Environment:
Darwin danmbp 25.4.0 Darwin Kernel Version 25.4.0: Thu Mar  5 22:05:44 PST 2026; root:xnu-12377.101.14~18/RELEASE_ARM64_T8142 arm64
>Description:
Currently, some packages such as fastfetch have an optional-but-enabled-by-default dependency on libdrm, which fails to compile on macOS (Darwin) due to the library simply not being supported on that platform. Building and installing the affected package(s) requires manually adding a line to mk.conf for any affected package:

PKG_OPTIONS.fastfetch=-libdrm

I don't know what pkgsrc's policy is on things like this, but given that installing libdrm on macOS is *never* going to work, not due to a bug, but due to a purposeful lack of support, is there any reason to ever assume that this library is enabled by default on macOS?
>How-To-Repeat:

>Fix: