Fixing Warnings

We need to ensure we don't overlap with the warning message fixing work. I've created:

https://wiki.yoctoproject.org/wiki/Warning_Fixing

which has a list of the remaining warnings I know about and has an indication of who (if anyone) is addressing them. Please check there before working on any given warning message.

The good news is we're down to about 115 of them for world assuming the pending patches merge.

I'm tempted to turn off the exec_prefix cross linkage warnings in the release branch for this release since the fixes for those could be too invasive to take the risk on at this point in the release cycle and most users probably don't need to see those warnings. Those warnings should be treated as the lowest priority.

Cheers,

Richard