sched: Introduce sched_wake_tasks() function to wake up tasks

Add function to indicate when tasks need to be run.  This will allow
the scheduler code to know if there are any tasks that need to be
processed.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/avr/serial.c

@@ -65,6 +65,8 @@ DECL_INIT(serial_init);
 ISR(USART0_RX_vect)
 {
     uint8_t data = UDR0;
+    if (data == MESSAGE_SYNC)
+        sched_wake_tasks();
     if (receive_pos >= sizeof(receive_buf))
         // Serial overflow - ignore it as crc error will force retransmit
         return;
@@ -104,6 +106,7 @@ console_pop_input(uint8_t len)
             memmove(&receive_buf[copied], &receive_buf[copied + len]
                     , needcopy - copied);
             copied = needcopy;
+            sched_wake_tasks();
         }
         irqstatus_t flag = irq_save();
         if (rpos != readb(&receive_pos)) {