bpf, s390: fix build for libbpf and selftest suite

The BPF feature test as well as libbpf is missing the __NR_bpf
define for s390 and currently refuses to compile (selftest suite
depends on libbpf as well). Similar issue was fixed some time
ago via b0c47807 ("bpf: Add sparc support to tools and
samples."), just do the same and add definitions.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/build/feature/test-bpf.c

@@ -11,6 +11,8 @@
 #  define __NR_bpf 280
 # elif defined(__sparc__)
 #  define __NR_bpf 349
+# elif defined(__s390__)
+#  define __NR_bpf 351
 # else
 #  error __NR_bpf not defined. libbpf does not support your arch.
 # endif

tools/lib/bpf/bpf.c

@@ -39,6 +39,8 @@
 #  define __NR_bpf 280
 # elif defined(__sparc__)
 #  define __NR_bpf 349
+# elif defined(__s390__)
+#  define __NR_bpf 351
 # else
 #  error __NR_bpf not defined. libbpf does not support your arch.
 # endif