srandomdev is *only* used to emulate arc4random, so only
bother defining it on Linux when it's needed. This avoids
unused errors on newer distros packaging glibc versions
that now defined arc4random.
Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I6e64a697d9633709cedd0198f75cf094d514562d
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/15814
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>