[oe] bitbake vs incremental builds

[Rich Pixley]

Looks like I got something wrong or got confused by the stamps earlier.  
I am seeing top-of-tree org.embedded.stable build more things after 
changes with BB_STAMP_POLICY = "full" than it was previously.

I'm also seeing that behavior in our environment now, although I'm not 
convinced we're doing all that people expect yet.  I'm planning to 
switch us over tomorrow morning.  We'll whether anything hits the fan then.

For this to be accurate, we need to eliminate all cases of "NOSTAMP", 
don't we?  Isn't the only reason to use NOSTAMP to force something to be 
redone every pass?

--rich