[flashrom-gerrit] Change in flashrom[master]: Makefile: Explicitly set '-std=c99 -D_GNU_SOURCE'

[Nico Huber (Code Review)]

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/47908 )

Change subject: Makefile: Explicitly set '-std=c99 -D_GNU_SOURCE'
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Patch Set 1:

Please always test such heavy changes on many host systems,
(e.g. with manibuilder) to make sure there's not more GNUism
than non-gnu systems can take.