Always build zipapex's unflattened.

Zipapex's cannot be flattened so do not prevent them from being built
even if TARGET_FLATTEN_APEX is set.

Test: lunch aosp_arm-eng;
      ALLOW_MISSING_DEPENDENCIES=true \
      ./art/tools/build_linux_bionic.sh com.android.runtime.host

Bug: 124333446
Change-Id: I4bef65cce100136a8f7852692e841b62ed9e399f
diff --git a/apex/apex.go b/apex/apex.go
index 0337afb..f4bc1b9 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -966,7 +966,7 @@
 	})
 
 	// Install to $OUT/soong/{target,host}/.../apex
-	if a.installable() && !ctx.Config().FlattenApex() {
+	if a.installable() && (!ctx.Config().FlattenApex() || apexType.zip()) {
 		ctx.InstallFile(android.PathForModuleInstall(ctx, "apex"), ctx.ModuleName()+suffix, a.outputFiles[apexType])
 	}
 }