Revert "Add override_module."

This reverts commit aa65e17016152d0d73cd10ab3987bc3bd5c2ef91.

Reason for revert: Not compatible with PRODUCT_PACKAGES, and so has very limited use.

Change-Id: Ib141d3984a6f12bb50989e66037494c466b066f1
diff --git a/android/config.go b/android/config.go
index 33986f7..24be10a 100644
--- a/android/config.go
+++ b/android/config.go
@@ -895,30 +895,16 @@
 }
 
 func (c *deviceConfig) OverrideManifestPackageNameFor(name string) (manifestName string, overridden bool) {
-	if newManifestName, overridden := c.manifestPackageNameOverrides().Load(name); overridden {
-		return newManifestName.(string), true
-	}
 	return findOverrideValue(c.config.productVariables.ManifestPackageNameOverrides, name,
 		"invalid override rule %q in PRODUCT_MANIFEST_PACKAGE_NAME_OVERRIDES should be <module_name>:<manifest_name>")
 }
 
 func (c *deviceConfig) OverrideCertificateFor(name string) (certificatePath string, overridden bool) {
-	if newCert, overridden := c.certificateOverrides().Load(name); overridden {
-		return newCert.(string), true
-	}
-	newCert, overridden := findOverrideValue(c.config.productVariables.CertificateOverrides, name,
+	return findOverrideValue(c.config.productVariables.CertificateOverrides, name,
 		"invalid override rule %q in PRODUCT_CERTIFICATE_OVERRIDES should be <module_name>:<certificate_module_name>")
-	if overridden {
-		// PRODUCT_CERTIFICATE_OVERRIDES only supports cert modules.
-		newCert = ":" + newCert
-	}
-	return newCert, overridden
 }
 
 func (c *deviceConfig) OverridePackageNameFor(name string) string {
-	if newName, overridden := c.moduleNameOverrides().Load(name); overridden {
-		return newName.(string)
-	}
 	newName, overridden := findOverrideValue(
 		c.config.productVariables.PackageNameOverrides,
 		name,