selftests/bpf: Use consistent build-id type for liburandom_read.so

lld produces "fast" style build-ids by default, which is inconsistent
with ld's "sha1" style. Explicitly specify build-id style to be "sha1"
when linking liburandom_read.so the same way it is already done for
urandom_read.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20221104094016.102049-1-asavkov@redhat.com