[automerger skipped] Add LICENSE file for libdrm am: 4a39b41b8b am: c33190098e -s ours

am skip reason: Merged-In Ia5bd5a907c21478e265218516c547549d98ea196 with SHA-1 4a39b41b8b is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libdrm/+/15069527

Change-Id: Ic61ea676b4e7bb2336ce4562dd2a25b6b4f84652