find-function-C-source-directory

[Lennart Borgman]

It is quite hard for those downloading prebuilt binaries of Emacs to 
view the C sources. Would it be possible to document somewhere in the 
manual how to do this through the help functions? Or, maybe better: 
could perhaps the help functions tell a bit about 
`find-function-C-source-directory '?

I think it could be relevant to fix this before the pretest since it 
might give more feedback.