BUILD: Enable system extensions to enable PTHREAD_MUTEX_RECURTSIVE.
BUILD: Enable system extensions to enable PTHREAD_MUTEX_RECURTSIVE.

 Using PTHREAD_MUTEX_RECURTSIVE on older systems requires extensions.

sergsagal1/ucx_rocm,sergsagal1/ucx_rocm,shssf/ucx,manjugv/ucx,abouteiller/ucx,miked-mellanox/ucx,miked-mellanox/ucx,sergsagal1/ucx_rocm,abouteiller/ucx,abouteiller/ucx,biddisco/ucx,biddisco/ucx,shssf/ucx,manjugv/ucx,shssf/ucx,miked-mellanox/ucx,abouteiller/ucx,manjugv/ucx,biddisco/ucx