Reducing library dependancies

[John Tapsell]

> Getting our dependencies straightened out and using symbolic-functions will
> help a lot more with startup time than -Wl,-as-needed (which is mostly a noop
> now with the link reduction in /trunk).

Could someone explain in more detail what this "link reduction" thing
is?  This is a cmake feature right?  What does it do and how does it
do it? :)

Thank you

John