[mesa] Remove conflict marker

This was left in Change-Id: Ifa7af9b210d0e093b4e1c8b35b2624704a9392fc.

Change-Id: Iba5e2bf688e67009f6c28499dac8ed1e8a924aaa
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/mesa/+/1176873
Reviewed-by: Craig Stout <cstout@google.com>
Commit-Queue: Craig Stout <cstout@google.com>
Reviewed-by: Josh Gargus <jjosh@google.com>