Introduce indirection layer on top Cronet ToT and Stable import channels

Export the RELEASE_ENABLE_TOT_CRONET build system flag as a Soong
variable. This way //external/cronet/Android.bp can make use of it (see
http://aosp/3507996).

Test: m
Bug: b:396593141
(cherry picked from https://android-review.googlesource.com/q/commit:6ba32ead11690889543d9ae82fe9547628b057a1)
Merged-In: Ib1ec49f3ccbcfd7b1232c8db658d0c80cb67a59a
Change-Id: Ib1ec49f3ccbcfd7b1232c8db658d0c80cb67a59a

NOTE FOR REVIEWERS - original patch and result patch are not identical.
PLEASE REVIEW CAREFULLY.
Diffs between the patches:
 # Use the configured version of Cronet
> +$(call soong_config_set,cronet,enable_cronet_tot,$(RELEASE_ENABLE_TOT_CRONET))
> +

Original patch:
 From 6ba32ead11690889543d9ae82fe9547628b057a1 Mon Sep 17 00:00:00 2001
From: Stefano Duo <stefanoduo@google.com>
Date: Fri, 21 Feb 2025 17:13:57 +0000
Subject: [PATCH] Introduce indirection layer on top Cronet ToT and Stable import channels

Export the RELEASE_ENABLE_TOT_CRONET build system flag as a Soong
variable. This way //external/cronet/Android.bp can make use of it (see
http://aosp/3507996).

Test: m
Bug: b:396593141
Change-Id: Ib1ec49f3ccbcfd7b1232c8db658d0c80cb67a59a
---

Result patch:
 diff --git a/target/product/build_variables.mk b/target/product/build_variables.mk
index c936911..7c54258 100644
--- a/target/product/build_variables.mk
+++ b/target/product/build_variables.mk
@@ -32,5 +32,8 @@
 # Use the configured MessageQueue implementation
 $(call soong_config_set, messagequeue, release_package_messagequeue_implementation, $(RELEASE_PACKAGE_MESSAGEQUEUE_IMPLEMENTATION))
 
+# Use the configured version of Cronet
+$(call soong_config_set,cronet,enable_cronet_tot,$(RELEASE_ENABLE_TOT_CRONET))
+
 # Use the configured version of WebView
 $(call soong_config_set, webview, release_package_webview_version, $(RELEASE_PACKAGE_WEBVIEW_VERSION))

Change-Id: Ia20f6d4212ae7dbd6343b09116133a4bbadf1fff