Add dual-controller AIO USB transport

tests/bluepad32_native_stubs/pico/critical_section.h

@@ -0,0 +1,7 @@
+#pragma once
+
+struct critical_section_t {};
+
+inline void critical_section_init(critical_section_t*) {}
+inline void critical_section_enter_blocking(critical_section_t*) {}
+inline void critical_section_exit(critical_section_t*) {}

tests/bluepad32_native_stubs/pico/cyw43_arch.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#define CYW43_WL_GPIO_LED_PIN 0
+
+int cyw43_arch_init();
+void cyw43_arch_gpio_put(int pin, bool value);

tests/bluepad32_native_stubs/pico/multicore.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void multicore_launch_core1(void (*entry)());

tests/bluepad32_native_stubs/pico/stdlib.h

@@ -0,0 +1,3 @@
+#pragma once
+
+inline void tight_loop_contents() {}