use C.UTF-8 locale for build environment

static/build.html

@@ -241,7 +241,6 @@
                             demanding tasks.</li>
                         <li>100GiB+ of additional free storage space for a typical build of the entire
                         OS for a multiarch device</li>
-                        <li>en_US.UTF-8 locale supported</li>
                     </ul>
 
                     <p>You can either obtain <code>repo</code> as a distribution package or the

static/releases.html

@@ -669,6 +669,7 @@
 
                     <ul>
                         <li>GmsCompatConfig: update max supported version of Play services</li>
+                        <li>use C.UTF-8 locale for build environment to avoid dependency of the en_US.UTF-8 locale being available</li>
                     </ul>
                 </article>
                 -->