gdb, gdbserver: make status_to_str display the signal name

I was looking at some "set debug lin-lwp" logs, and saw that a thread
received the "Child exited" signal.  It took me a moment to realize that
this was SIGCHLD.  I then thought that it would be nice for
status_to_str to show the signal name (SIGCHLD) in addition to the
description "Child exited", since people are much more used to referring
to signals using their names.

Fortunately, libiberty contains a handy function to get the signal name
from the signal number, strsigno, use that.

The output of "set debug lin-lwp" now looks like:

    [linux-nat] linux_nat_wait_1: waitpid 1209631 received SIGTRAP - Trace/breakpoint trap (stopped)

gdb/ChangeLog:

	* nat/linux-waitpid.c (status_to_str): Show signal name.

Change-Id: I8ad9b1e744dd64461fd87b08d5c29f9ef97c4691

1 files changed, 6 insertions, 4 deletions

diff --git a/gdb/nat/linux-waitpid.c b/gdb/nat/linux-waitpid.c
index f205df7..9948904 100644
--- a/gdb/nat/linux-waitpid.c
+++ b/gdb/nat/linux-waitpid.c
@@ -32,14 +32,16 @@ status_to_str (int status)
   if (WIFSTOPPED (status))
     {
       if (WSTOPSIG (status) == SYSCALL_SIGTRAP)
-	return string_printf ("%s (stopped at syscall)",
-			      strsignal (SIGTRAP));
+	return string_printf ("%s - %s (stopped at syscall)",
+			      strsigno (SIGTRAP), strsignal (SIGTRAP));
       else
-	return string_printf ("%s (stopped)",
+	return string_printf ("%s - %s (stopped)",
+			      strsigno (WSTOPSIG (status)),
 			      strsignal (WSTOPSIG (status)));
     }
   else if (WIFSIGNALED (status))
-    return string_printf ("%s (terminated)",
+    return string_printf ("%s - %s (terminated)",
+			  strsigno (WTERMSIG (status)),
 			  strsignal (WTERMSIG (status)));
   else
     return string_printf ("%d (exited)", WEXITSTATUS (status));