Introduce sys_sigprocmask and sys_sigaction.

sandbox/linux/seccomp-bpf/trap.h

Index: sandbox/linux/seccomp-bpf/trap.h
diff --git a/sandbox/linux/seccomp-bpf/trap.h b/sandbox/linux/seccomp-bpf/trap.h
index 4073bfe1201caa067ba6728672b316e84d1227e0..1d501b486f4ddf2b30d5d144d5a2b1d4b38abda4 100644
--- a/sandbox/linux/seccomp-bpf/trap.h
+++ b/sandbox/linux/seccomp-bpf/trap.h
@@ -12,6 +12,7 @@
 
 #include "base/macros.h"
 #include "sandbox/linux/bpf_dsl/trap_registry.h"
+#include "sandbox/linux/system_headers/linux_signal.h"
 #include "sandbox/sandbox_export.h"
 
 namespace sandbox {
@@ -57,11 +58,11 @@ class SANDBOX_EXPORT Trap : public bpf_dsl::TrapRegistry {
   // break subsequent system calls that trigger a SIGSYS.
   ~Trap() = delete;
 
-  static void SigSysAction(int nr, siginfo_t* info, void* void_context);
+  static void SigSysAction(int nr, LinuxSigInfo* info, void* void_context);
 
   // Make sure that SigSys is not inlined in order to get slightly better crash
   // dumps.
-  void SigSys(int nr, siginfo_t* info, void* void_context)
+  void SigSys(int nr, LinuxSigInfo* info, void* void_context)
       __attribute__((noinline));
   // We have a global singleton that handles all of our SIGSYS traps. This
   // variable must never be deallocated after it has been set up initially, as