NDK: Last cleanup of the platform headers

- fix a declaration omission in 3/<grp.h>
- add missing 8/<err.h>
- simplify 8/<stdio.h>
- update 9/ headers to the latest Bionic versions
- fix a typo in android_native_app_glue.h
- use __BEGIN_DECLS .. __END_DECLS whenever possible.
- remove C++-style comments from headers

Change-Id: I58b98b3973cde494436206194ba33416a11ca8ee

ndk/platforms/android-9/include/android/sensor.h

@@ -39,14 +39,12 @@
  * native code.
  *
  */
-
+#include <sys/cdefs.h>
 #include <sys/types.h>
 
 #include <android/looper.h>
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+__BEGIN_DECLS
 
 
 /*
@@ -249,8 +247,6 @@ float ASensor_getResolution(ASensor const* sensor);
 int ASensor_getMinDelay(ASensor const* sensor);
 
 
-#ifdef __cplusplus
-};
-#endif
+__END_DECLS
 
-#endif // ANDROID_SENSOR_H
+#endif /* ANDROID_SENSOR_H */