Replace env!("...") expressions

* Use new regen_bp.sh to find/fix env!("...") expressions
* No need of local diff file or post_update.sh because
  regen_bp.sh will fix any old/new env!("...") expressions.

Bug: 172299943
Test: build all rust crates
Change-Id: Iad59cdf6318e5163012fc7b05fd1bdd2a523979e
diff --git a/src/lib.rs b/src/lib.rs
index 6c33538..8e519d4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -192,7 +192,7 @@
     {
         let mut w = CodeWriter::new(&mut v);
 
-        w.write_generated_by("rust-protobuf", "2.18.0"); // ANDROID ported version
+        w.write_generated_by("rust-protobuf", "2.18.0");
         w.write_line(&format!("//! Generated file from `{}`", file.get_name()));
         if customize.inside_protobuf != Some(true) {
             w.write_line("");