Change in coreboot[master]: [WIP]Allow to build romstage sources inside the bootblock

[Aaron Durbin (Code Review)]

Attention is currently required from: Arthur Heymans, Raul Rangel, Furquan Shaikh, Philipp Hug, ron minnich, Stefan Reinauer, Angel Pons, Subrata Banik, Julius Werner, Andrey Petrov, Patrick Rudolph, Piotr Król, Jason Glenesk, Michał Żygowski, Martin Roth, Marshall Dawson, Ron Minnich, Felix Held.
Aaron Durbin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/55068 )

Change subject: [WIP]Allow to build romstage sources inside the bootblock
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Patch Set 4:

(1 comment)

Patchset:

PS4: 
Could you please elaborate on what diligence was done in the analysis w.r.t. semantics of existing code? I know we've built a lot of infrastructure around ENV_x, etc. This change obviously allows previously mutually exclusive settings to coexist.