sh: Do not read from stdin if an error occurs during -i -c cmd.

Although using -i with -c does not seem very useful, it seems inappropriate
to read commands from the terminal in this case.

Side effect: if the -s -c extension is used and the -s option is turned off
using 'set +s' during the interactive part, the shell now exits after an
error or interrupt. Note that POSIX only specifies -s as option to sh, not
to set.

See also Austin Group issue #718.

bin/sh/main.c

@@ -170,8 +170,8 @@ main(int argc, char *argv[])
 	if (minusc) {
 		evalstring(minusc, sflag ? 0 : EV_EXIT);
 	}
+state4:
 	if (sflag || minusc == NULL) {
-state4:	/* XXX ??? - why isn't this before the "if" statement */
 		cmdloop(1);
 	}
 	exitshell(exitstatus);

tools/regression/bin/sh/execution/int-cmd1.0

@@ -0,0 +1,3 @@
+# $FreeBSD$
+
+! echo echo bad | $SH -ic 'fi' 2>/dev/null