NdkMediaFormat.h: Updated to include Android API macros

On host toolchains, Android API macros like __ANDROID_API__ and
__INTRODUCED_IN are not available as 'sys/cdefs.h' is different
between Android and host.
Hence they have been added if they are not previously defined.

Test: Build libmediandk
Bug: 151789258

Change-Id: I74c808a45c718e312bd36db39dafd4bb15a7f37b