Let -c imply -S (hide signal output).

Without this, the signals are shown seemingly randomly in the output before
the final summary is shown.  This is especially noticeable when there is
not much output from the application being traced.

Discussed with:	jhb
Relnotes:	yes

usr.bin/truss/main.c

@@ -111,7 +111,7 @@ main(int ac, char **av)
 			trussinfo->flags |= EXECVEARGS;
 			break;
 		case 'c': /* Count number of system calls and time. */
-			trussinfo->flags |= COUNTONLY;
+			trussinfo->flags |= (COUNTONLY | NOSIGS);
 			break;
 		case 'e': /* Print execve() environment strings. */
 			trussinfo->flags |= EXECVEENVS;

usr.bin/truss/truss.1

@@ -1,6 +1,6 @@
 .\" $FreeBSD$
 .\"
-.Dd October 5, 2015
+.Dd October 9, 2015
 .Dt TRUSS 1
 .Os
 .Sh NAME
@@ -37,7 +37,7 @@ Show the argument strings that are passed in each
 .Xr execve 2
 system call.
 .It Fl c
-Do not display individual system calls.
+Do not display individual system calls or signals.
 Instead, before exiting, print a summary containing for each system call:
 the total system time used,
 the number of times the call was invoked,