selftests/bpf: fix RELEASE=1 build for tc_opts

Compiler complains about malloc(). We also don't need to dynamically
allocate anything, so make the life easier by using statically sized
buffer.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-2-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/prog_tests/tc_opts.c

@@ -2387,12 +2387,9 @@ static int generate_dummy_prog(void)
 	const size_t prog_insn_cnt = sizeof(prog_insns) / sizeof(struct bpf_insn);
 	LIBBPF_OPTS(bpf_prog_load_opts, opts);
 	const size_t log_buf_sz = 256;
-	char *log_buf;
+	char log_buf[log_buf_sz];
 	int fd = -1;
 
-	log_buf = malloc(log_buf_sz);
-	if (!ASSERT_OK_PTR(log_buf, "log_buf_alloc"))
-		return fd;
 	opts.log_buf = log_buf;
 	opts.log_size = log_buf_sz;
 
@@ -2402,7 +2399,6 @@ static int generate_dummy_prog(void)
 			   prog_insns, prog_insn_cnt, &opts);
 	ASSERT_STREQ(log_buf, "", "log_0");
 	ASSERT_GE(fd, 0, "prog_fd");
-	free(log_buf);
 	return fd;
 }