selftests/seccomp: Fix compile warning when CC=clang

clang has -Wconstant-conversion by default, and the constant 0xAAAAAAAAA
(9 As) being converted to an int, which is generally 32 bits, results
in the compile warning:

clang -Wl,-no-as-needed -Wall -isystem ../../../../usr/include/ -lpthread seccomp_bpf.c -lcap -o seccomp_bpf
seccomp_bpf.c:812:67: warning: implicit conversion from 'long' to 'int' changes value from 45812984490 to -1431655766 [-Wconstant-conversion]
int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
~~~~ ^~~~~~~~~~~
1 warning generated.

-1431655766 is the expected truncation, 0xAAAAAAAA (8 As), so use
this directly in the code to avoid the warning.

Fixes: 3932fcecd962 ("selftests/seccomp: Add test for unknown SECCOMP_RET kill behavior")
Signed-off-by: YiFei Zhu <[e-mail]>
Signed-off-by: Kees Cook <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/seccomp/seccomp_bpf.c

···
 		.len = (unsigned short)ARRAY_SIZE(filter_thread),
 		.filter = filter_thread,
 	};
-	int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
+	int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAA;
 	struct sock_filter filter_process[] = {
 		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
 			offsetof(struct seccomp_data, nr)),