configure: Provide symlink for amdgcn-mesa3d instead of configure hack

Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-By: Aaron Watry <awatry@gmail.com>
llvm-svn: 346085
GitOrigin-RevId: fd9d787b183a58295b621e375a35246e74340639
2 files changed