msm8916-mainline/lk2nd ? reverse-engineered prompt

Build me lk2nd from this repo for a Qualcomm MSM8916 device and make sure it boots cleanly as a secondary bootloader from an Android boot image. I want the project to compile without errors, and if anything in the current setup is unclear, please look up the latest build docs online and use the right toolchain and build command for this codebase.

After it builds, I’d like a ready to flash lk2nd.img and a short note on how to flash it with fastboot or, if needed, Samsung style flashing. If there are any obvious tweaks needed for a specific device or board config, please point them out and make the default setup as close to working as possible. Also keep the fastboot and recovery key behavior working, and don’t break the ability to flash a real boot image with the expected offset.