Connect fingerprint build flag to soong.

When RELEASE_FINGERPRINT_ACONFIG_PACKAGE is true, the storage file
version will be v2 for aconfig create-storage.

Test: manual
Change-Id: I6861ac1bfe8680ff7311e26efb627e0ac7c58f05
diff --git a/android/config.go b/android/config.go
index d78bbf7..a660baa 100644
--- a/android/config.go
+++ b/android/config.go
@@ -289,6 +289,10 @@
 	return c.config.productVariables.GetBuildFlagBool("RELEASE_USE_SYSTEM_FEATURE_BUILD_FLAGS")
 }
 
+func (c Config) ReleaseFingerprintAconfigPackages() bool {
+	return c.config.productVariables.GetBuildFlagBool("RELEASE_FINGERPRINT_ACONFIG_PACKAGES")
+}
+
 // A DeviceConfig object represents the configuration for a particular device
 // being built. For now there will only be one of these, but in the future there
 // may be multiple devices being built.