[Buildroot] [PATCH] core/reproducible: do not override SOURCE_DATE_EPOCH

[Peter Korsgaard]

>>>>> "Yann" == Yann E MORIN <yann.morin.1998 at free.fr> writes:

 > SOURCE_DATE_EPOCH is currently forcibly set (to either the git commit
 > date, or the last release date).

 > However, the spec mandates that it should not be modified if already
 > set: https://reproducible-builds.org/specs/source-date-epoch/

 >     Build systems MUST NOT overwrite this variable for child
 >     processes to consume if it is already present.

 > Abide by the rule, and only set it if not already set.

 > This will allow users to pass it from an upper-layer buildsystem (e.g. a
 > jenkins or gitlab-ci job, for example), when they have a reson to do so.

 > Reported-by: Peter Korsgaard <peter at korsgaard.com>
 > Reported-by: Einar Jón Gunnarsson <tolvupostur at gmail.com>
 > Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
 > Cc: Peter Korsgaard <peter at korsgaard.com>
 > Cc: Einar Jón Gunnarsson <tolvupostur at gmail.com>
 > Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
 > Cc: Arnout Vandecappelle <arnout at mind.be>

Committed, thanks.

-- 
Bye, Peter Korsgaard