Fix NdkImage.h includes

It needs stdint.h.

It's OK to include android/hardware_buffer.h on pre-26. We'd like to remove
the __ANDROID_API__ guard around AImage_getHardwareBuffer, and if/when we
do, we'll need android/hardware_buffer.h. The last time we removed the
__ANDROID_API__ guards around the APIs, we forgot to remove the one around
this #include.

Bug: http://b/111130072#comment12
Bug: http://b/113052379
Test: builds
Change-Id: Ice8073476d4ad4802e3540f15eee3af29e0b891f
Merged-In: Ice8073476d4ad4802e3540f15eee3af29e0b891f
(cherry picked from commit c2039dc505)

media/ndk/include/media/NdkImage.h

@@ -36,13 +36,12 @@
 #ifndef _NDK_IMAGE_H
 #define _NDK_IMAGE_H
 
+#include <stdint.h>
 #include <sys/cdefs.h>
 
 #include "NdkMediaError.h"
 
-#if __ANDROID_API__ >= 26
 #include <android/hardware_buffer.h>
-#endif /* __ANDROID_API__ >= 26 */
 
 __BEGIN_DECLS