Remove global state on module suffixes from vendor and recovery snapshots

Propgate the Android.mk suffix from source modules into the snapshot so
that it can be used for the prebuilt modules.

Bug: 177098205
Test: vendor_snapshot_test.go
Change-Id: Iea151dc91395f714fbcad1df3a6fd0874e5455d9

cc/image.go

@@ -318,9 +318,7 @@ func (m *Module) ImageMutatorBegin(mctx android.BaseModuleContext) {
 	} else if m.isSnapshotPrebuilt() {
 		// Make vendor variants only for the versions in BOARD_VNDK_VERSION and
 		// PRODUCT_EXTRA_VNDK_VERSIONS.
-		if snapshot, ok := m.linker.(interface {
-			version() string
-		}); ok {
+		if snapshot, ok := m.linker.(snapshotInterface); ok {
 			if m.InstallInRecovery() {
 				recoveryVariantNeeded = true
 			} else {