Request for backporting rtla fix into 6.15-stable

Hello,

Please pull the following upstream patch to 6.15-stable:

8020361d51ee "rtla: Define _GNU_SOURCE in timerlat_bpf.c"

This fixes an rtla bug that was introduced in 6.15 and was expected to be merged into 6.15, hence it was not tagged with Cc: stable, but did not make it.

Thanks, Tomas