[NaCl SDK] nacl_io: Add initial implementations of kill and signal

native_client_sdk/src/libraries/nacl_io/syscalls/signal.c

Index: native_client_sdk/src/libraries/nacl_io/syscalls/signal.c
diff --git a/native_client_sdk/src/libraries/nacl_io/syscalls/recvmsg.c b/native_client_sdk/src/libraries/nacl_io/syscalls/signal.c
similarity index 72%
copy from native_client_sdk/src/libraries/nacl_io/syscalls/recvmsg.c
copy to native_client_sdk/src/libraries/nacl_io/syscalls/signal.c
index 99cdd3a5a39d0069a39dbba5154a3019bc3e4ef1..a111add8938f9cbe3f301cb44c700452332bc275 100644
--- a/native_client_sdk/src/libraries/nacl_io/syscalls/recvmsg.c
+++ b/native_client_sdk/src/libraries/nacl_io/syscalls/signal.c
@@ -5,6 +5,6 @@
 #include "nacl_io/kernel_intercept.h"
 #include "nacl_io/kernel_wrap.h"
 
-ssize_t recvmsg(int fd, struct msghdr* msg, int flags) {
-  return ki_recvmsg(fd, msg, flags);
+sighandler_t signal(int signum, sighandler_t handler) {
+  return ki_signal(signum, handler);
 }