Bug 1893181 - Enforce buildToolsVersion from toplevel Gradle project too. r=nalexander

The resolution of bug 1906365 was incomplete, the buildToolsVersion was
not enforced when building AC, Fenix or Focus from the toplevel Gradle
project.

Differential Revision: https://phabricator.services.mozilla.com/D221845

build.gradle

@@ -135,6 +135,14 @@ allprojects {
         ]
     }
 
+    afterEvaluate {
+        if (it.hasProperty('android')) {
+            android {
+                buildToolsVersion gradle.mozconfig.substs.ANDROID_BUILD_TOOLS_VERSION
+            }
+        }
+    }
+
     repositories {
         gradle.mozconfig.substs.GRADLE_MAVEN_REPOSITORIES.each { repository ->
             maven {