[S] Change in flashrom[master]: libflashrom: Allow getting the progress_state from the flashctx

[Angel Pons (Code Review)]

Attention is currently required from: Felix Singer, Nico Huber, Richard Hughes, Edward O'Callaghan, Daniel Campello, Anastasia Klimchuk.

Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/64663 )

Change subject: libflashrom: Allow getting the progress_state from the flashctx
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Patch Set 2: Code-Review+1

(1 comment)

File include/libflashrom.h:

https://review.coreboot.org/c/flashrom/+/64663/comment/22dd8368_42ed6ead 
PS2, Line 85: typedef void(flashrom_progress_callback)(struct flashrom_flashctx *flashctx);
> But struct flashrom_flashctx is opaque, so there's only one state effectively. […]

Nico, if we understand you correctly, flashctx should be kept internal, and the API should have a different `user_data` struct. Is this correct?