input: Cleanup doxygen linking

This goes through the file and adds either `#` or `{@link ...}` doxygen
linkage for all enum values, types, and functions to allow deep linking
to be generated.

Test: `development/tools/ndk/build_ndk_docs.py` and manual inspection of the generated doc.
Change-Id: I0b6a154c9ba2cb4749d007b22088675667b6d7b4