Implement seccomp decoding

* configure.ac (AC_CHECK_HEADERS): Add linux/filter.h
and linux/seccomp.h.
* defs.h (print_seccomp_filter): New prototype.
* linux/dummy.h (sys_seccomp): Remove.
* linux/syscall.h (sys_seccomp): New prototype.
* prctl.c: Include <linux/seccomp.h>.
(sys_prctl): Decode PR_SET_SECCOMP.
* seccomp.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* xlat/bpf_class.in: New file.
* xlat/bpf_miscop.in: Likewise.
* xlat/bpf_mode.in: Likewise.
* xlat/bpf_op_alu.in: Likewise.
* xlat/bpf_op_jmp.in: Likewise.
* xlat/bpf_rval.in: Likewise.
* xlat/bpf_size.in: Likewise.
* xlat/bpf_src.in: Likewise.
* xlat/seccomp_filter_flags.in: Likewise.
* xlat/seccomp_mode.in: Likewise.
* xlat/seccomp_ops.in: Likewise.
* xlat/seccomp_ret_action.in: Likewise.
diff --git a/Makefile.am b/Makefile.am
index bb2cae2..38cb08b 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -86,6 +86,7 @@
 	resource.c	\
 	sched.c		\
 	scsi.c		\
+	seccomp.c	\
 	signal.c	\
 	sock.c		\
 	socketutils.c	\