Camera NDK: fix headers

- Include stdbool.h for using bool in C
- Add typedef to restore backward compatibility

Bug: https://github.com/android-ndk/ndk/issues/559
Change-Id: I28f5a99ea6271e364a2d1db793dbadcc63fe2f2c

camera/ndk/include/camera/NdkCameraCaptureSession.h

@@ -33,6 +33,7 @@
  * Do not #include files that aren't part of the NDK.
  */
 #include <sys/cdefs.h>
+#include <stdbool.h>
 
 #include <android/native_window.h>
 #include "NdkCameraError.h"

camera/ndk/include/camera/NdkCameraDevice.h

@@ -152,6 +152,11 @@ typedef struct ACameraDevice_StateCallbacks {
     ACameraDevice_ErrorStateCallback  onError;
 } ACameraDevice_StateCallbacks;
 
+/**
+ * For backward compatiblity.
+ */
+typedef ACameraDevice_StateCallbacks ACameraDevice_stateCallbacks;
+
 /**
  * Close the connection and free this ACameraDevice synchronously. Access to the ACameraDevice
  * after calling this method will cause a crash.