selftests: bpf: break up test_verifier

Break up the first 10 kLoC of test verifier test cases
out into smaller files.  Looks like git line counting
gets a little flismy above 16 bit integers, so we need
two commits to break up test_verifier.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/verifier/basic.c

@@ -0,0 +1,23 @@
+{
+	"empty prog",
+	.insns = {
+	},
+	.errstr = "unknown opcode 00",
+	.result = REJECT,
+},
+{
+	"only exit insn",
+	.insns = {
+	BPF_EXIT_INSN(),
+	},
+	.errstr = "R0 !read_ok",
+	.result = REJECT,
+},
+{
+	"no bpf_exit",
+	.insns = {
+	BPF_ALU64_REG(BPF_MOV, BPF_REG_0, BPF_REG_2),
+	},
+	.errstr = "not an exit",
+	.result = REJECT,
+},