audio/mumble: fixed dependencies after update devel/protobuf to 24.x

After update devel/protobuf to 24.x mumble started link with dosen
libabsl_*.so from devel/abseil.
While here: audio/mumble doesn't use GL - remove it from dependencies.

Approved by: arrowd (mentor, implicit)
MFH: 2024Q1

(cherry picked from commit b29347d0d51a7583aa87acdb3fa425022b8c0c1d)