sched/signal: Add support for SIGINT in addition to SIGKILL. drivers/serial: Use SIGINT instead of SIGKILL when control-C is pressed.

include/nuttx/serial/serial.h

@@ -286,8 +286,8 @@ struct uart_dev_s
   tcflag_t             tc_iflag;     /* Input modes */
   tcflag_t             tc_oflag;     /* Output modes */
   tcflag_t             tc_lflag;     /* Local modes */
-#ifdef CONFIG_TTY_SIGKILL
-  pid_t                pid;          /* Thread PID to receive SIGKILL signals (-1 if none) */
+#ifdef CONFIG_TTY_SIGINT
+  pid_t                pid;          /* Thread PID to receive SIGINT signals (-1 if none) */
 #endif
 #endif
 

include/signal.h

@@ -170,8 +170,13 @@
 #endif
 
 #ifdef CONFIG_SIG_DEFAULT
+#  ifndef CONFIG_SIG_INT
+#    define SIGINT      6  /* Sent when ctrl-c event  */
+#  else
+#    define SIGINT      CONFIG_SIG_INT
+#  endif
 #  ifndef CONFIG_SIG_KILL
-#    define SIGKILL     9  /* Sent when ctrl-c event (vs. standard SIGINT)  */
+#    define SIGKILL     9  /* Sent from shell as 'kill -9 <task>'  */
 #  else
 #    define SIGKILL     CONFIG_SIG_KILL
 #  endif