I noticed this document has not made it to the new Wiki:
https://wiki.openwrt.org/doc/devel/crosscompile
Its instructions are very helpful in compiling a single source file. @tmomas asssted with this before. Is it possible it can be moved as well?
Thanks!
@bobafetthotmail Where (which section) would this fit into https://openwrt.org/docs/guide-developer/start ?
Hm, it was moved alright, https://openwrt.org/docs/guide-developer/crosscompile but was not linked from the Developer documentation page (so it was not accessible). Now it's available from the "Using the Toolchain" section.
Thanks for pointing out it was missing. Sorry for the inconvenience. 
Thanks. I appreciate the work.