sys/ptrace.h: add PTRACE_SECCOMP_GET_METADATA from linux v4.16

to get seccomp state for checkpoint restore.
added in linux commit 26500475ac1b499d8636ff281311d633909f5d20

struct tag follows the glibc api and ptrace_peeksiginfo_args
got changed too accordingly.

include/sys/ptrace.h

@@ -40,6 +40,7 @@ extern "C" {
 #define PTRACE_GETSIGMASK 0x420a
 #define PTRACE_SETSIGMASK 0x420b
 #define PTRACE_SECCOMP_GET_FILTER 0x420c
+#define PTRACE_SECCOMP_GET_METADATA 0x420d
 
 #define PT_READ_I PTRACE_PEEKTEXT
 #define PT_READ_D PTRACE_PEEKDATA
@@ -86,12 +87,17 @@ extern "C" {
 
 #define PTRACE_PEEKSIGINFO_SHARED 1
 
-struct ptrace_peeksiginfo_args {
+struct __ptrace_peeksiginfo_args {
 	uint64_t off;
 	uint32_t flags;
 	int32_t nr;
 };
 
+struct __ptrace_seccomp_metadata {
+	uint64_t filter_off;
+	uint64_t flags;
+};
+
 long ptrace(int, ...);
 
 #ifdef __cplusplus