Non-SFI mode: Add Linux asynchronous signal support

src/nonsfi/linux/linux_sys_private.c

Index: src/nonsfi/linux/linux_sys_private.c
diff --git a/src/nonsfi/linux/linux_sys_private.c b/src/nonsfi/linux/linux_sys_private.c
index 00cc97b804918d9da3f7609f074ffcc0458c9cbc..5d90da9430a5c8f9929085f95d3014bfc459518c 100644
--- a/src/nonsfi/linux/linux_sys_private.c
+++ b/src/nonsfi/linux/linux_sys_private.c
@@ -610,6 +610,13 @@ int linux_sigprocmask(int how,
                      sizeof(*set)));
 }
 
+int linux_tgkill(int tgid,

[Mark Seaborn, 2015/06/26 18:31:59]

Nit: args would fit on one line

[Luis Héctor Chávez, 2015/07/06 23:44:59]

Done.

+                 int tid,
+                 int sig) {
+  return errno_value_call(
+      linux_syscall3(__NR_tgkill, tgid, tid, sig));
+}
+
 /*
  * Obtain Linux signal number from portable signal number.
  */