scripts: add bpf/syscalls.bt

This script counts how many times each syscall
is called by the SPDK application.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Ife5efccee73e407e1d819293786f2acdfa317f78
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/7713
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>

scripts/bpf/syscalls.bt

@@ -0,0 +1,3 @@
+tracepoint:syscalls:sys_enter_* /pid == __PID__/ {
+	@syscall[probe] = count();
+}