distro/rhel85: don't copy architecture when adding it to a distro

Originally, a copy of an architecture instance was always created when it
was added to a distro definition using the `addArches()` method.
However in reality, only a subset of structure members were copied,
which could create unexpected behavior and issues. This behavior is
identical to the behavior when image types are added to an architecture.
However the situation with image types differs in one aspect,
specifically that a single image type definition is usually reused
by multiple architecture definitions, while an architecture definition
is always used only by a single distribution definition.
Due to the fact that the image type contains a reference to the
architecture to which it has been added, the creation of a copy can not
be reasonably avoided. On the other hand, adding a copy of an architecture
to a distribution definition is not necessary.

Downside of creating copies of the architecture is that the image types
associated with it referred always to the original architecture
definition instance and not to the copy. So while references in the
direction of Distro -> Arch -> Image Type were correct and working, the
other direction was broken. Image Type -> (original) Arch -> (nil)
Distro.

Modify `distribution.AddArches()` method to directly add the passed
architecture instances to the distribution definition, instead of adding
their copies.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

internal/distro/rhel85/distro.go

@@ -88,12 +88,11 @@ func (d *distribution) addArches(arches ...architecture) {
 		d.arches = map[string]distro.Arch{}
 	}
 
-	for _, a := range arches {
-		d.arches[a.name] = &architecture{
-			distro:     d,
-			name:       a.name,
-			imageTypes: a.imageTypes,
-		}
+	// Do not make copies of architectures, as opposed to image types,
+	// because architecture definitions are not used by more than a single
+	// distro definition.
+	for idx := range arches {
+		d.arches[arches[idx].name] = &arches[idx]
 	}
 }