internal/rosa: export source kind

This is set for an exported field, so export the constants as well.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/rosa.go

@@ -426,8 +426,8 @@ type Helper interface {
 }
 
 const (
-	// sourceTarXZ denotes a source tarball to be decompressed using [XZ].
-	sourceTarXZ = 1 + iota
+	// SourceKindTarXZ denotes a source tarball to be decompressed using [XZ].
+	SourceKindTarXZ = 1 + iota
 )
 
 // PackageAttr holds build-system-agnostic attributes.
@@ -546,7 +546,7 @@ func (t Toolchain) NewPackage(
 
 	var sourceSuffix string
 	switch attr.SourceKind {
-	case sourceTarXZ:
+	case SourceKindTarXZ:
 		sourceSuffix = ".tar.xz"
 		scriptEarly += `
 tar -C /usr/src/ -xf '/usr/src/` + name + `.tar.xz'