Camera NDK: Fix broken header doc links

It appears that doxygen header links are not supported by
the developer site generation scripts.
Replace the NDK header links with valid URLs.

Bug: 172600451
Test: Generate doxygen docs via "development/tools/ndk/build_ndk_docs.py",
check doc output

Change-Id: I69fa3f0b2dc9fa563088bd4d74f16b7f1d2d890a