In order to protect users of prebid-server that don't use CGO, add build flag

[scr-oath]

Changes between v2.30.0...v2.31.0 force users to use CGO, even if not using the 51degrees module. This change adds the cgo flag to enable bringing in prebid-server without this requirement.

[jwrosewell]

Thank you for the additions and looks good with the changes from @justadreamer.

[scr-oath]

@bsardo - how can we move this forward?

[SyntaxNode]

@linux019 - You commented on this PR. Do you wish to re-review?

[linux019]

@SyntaxNode
I would use build tags to exclude code which cannot be used without native library. Instead of this we have successfully compiled image which has passed all unit tests but might crash on startup depending on PBS configuration.

If the PBS cannot be run without CGO - don't allow to build the image instead of raising a panic or exclude compiler-depended code
To include module we can use this build tag

//go:build cgo

[scr-oath]

@SyntaxNode @linux019 - please take another look - the fiftyonedegrees module is excluded in its entirety now (though, there still needs to be cgo and !cgo files in the modules for the builder to conditionally configure it.

[linux019]

This file is autogenerated by

prebid-server/Makefile

Line 23 in f3b5bce

go generate modules/modules.go