Update test for bpf raw tracepoints to work with Linux 5.7 kernels

Update test for bpf raw tracepoints to work with Linux 5.7 kernels

The kernel commit 70ed506c3bbcfa846d4636b23051ca79fa4781f7 in Linux
5.7 and newer replaced the bpf_raw_tracepoint_release function with
bpf_raw_tp_link_release.  This change in function names would cause
SystemTap's test for BPF raw tracepoint support to fail.  Updated the
check to look for the newer alternative function name.