There's a closed pull request on the void-packages repository

mupdf: add clipboard build option
https://github.com/void-linux/void-packages/pull/39801

Description:
This option enables clipboard support in mupdf-gl by building with the vendored copy of freeglut instead of the system copy.

Fixes: #13871

#### Testing the changes
- I tested the changes in this PR: **YES**

#### Local build testing
- I built this PR locally for my native architecture, x84_64-glibc
- I built this PR locally for these architectures:
  - aarch64-musl (cross)
  - armv7l (cross)
  - armv6l-musl (cross)