common/environment/build-style/go.sh: allow setting CGO_ENABLED

[sug0]

Change hard-coded value of CGO_ENABLED to allow reading a user configured value from a template file. This is required to fix a segmentation fault in #40919, derived from some kind of linking error. The default behavior is kept, i.e. cgo is still enabled by default, which shouldn't break any packages.

Testing the changes

• I tested the changes in this PR: briefly

[Vaelatern]

Why :-?

[sug0]

I found it the most practical way to maintain the old value, if CGO_ENABLED was not set in the env
@Vaelatern is there any issue with using ${VAR:-$DEFAULT_VALUE}?

[Vaelatern]

makes it look like you mean negative instead of :=

[classabbyamp]

:- and := do different things, :- wil substitute the default if null or unset, := will assign the default if null or unset. which is the desired behaviour?

In all cases shown with "substitute", the expression is replaced with the value shown. In all cases shown with "assign", parameter is assigned that value, which also replaces the expression.

[sug0]

:- seems like the best option here. := will do two assignments, since CGO_ENABLED is set again and exported on the left. either way, both would work here. can you tell me which of the two you prefer?

:- and := do different things, :- wil substitute the default if null or unset, := will assign the default if null or unset. which is the desired behaviour?

In all cases shown with "substitute", the expression is replaced with the value shown. In all cases shown with "assign", parameter is assigned that value, which also replaces the expression.

[Vaelatern]

@classabbyamp I'm ok either way, you want to merge?

[sug0]

cheers