ports: Call gc_sweep_all() when doing a soft reset.

This calls finalisers of things like files and sockets to cleanly close
them.

ports/esp32/main.c

@@ -116,6 +116,8 @@ soft_reset:
     mp_thread_deinit();
     #endif
 
+    gc_sweep_all();
+
     mp_hal_stdout_tx_str("PYB: soft reboot\r\n");
 
     // deinitialise peripherals

ports/esp8266/main.c

@@ -88,6 +88,7 @@ STATIC void mp_reset(void) {
 }
 
 void soft_reset(void) {
+    gc_sweep_all();
     mp_hal_stdout_tx_str("PYB: soft reboot\r\n");
     mp_hal_delay_us(10000); // allow UART to flush output
     mp_reset();

ports/stm32/main.c

@@ -756,5 +756,7 @@ soft_reset_exit:
     pyb_thread_deinit();
     #endif
 
+    gc_sweep_all();
+
     goto soft_reset;
 }

ports/unix/main.c

@@ -647,6 +647,10 @@ MP_NOINLINE int main_(int argc, char **argv) {
     }
     #endif
 
+    #if defined(MICROPY_UNIX_COVERAGE)
+    gc_sweep_all();
+    #endif
+
     mp_deinit();
 
 #if MICROPY_ENABLE_GC && !defined(NDEBUG)