Revert ac1bf46 which ends up disabling rerun-if-changed for src/*.rs

This ran into a known cargo footgun where if you emit rerun-if-changed
you are responsible for emitting all the rerun-if-changed directives that
otherwise would be implied by cargo.

Author: ratmice

lrlex/src/lib/ctbuilder.rs

@@ -355,9 +355,6 @@ where
             .lexer_path
             .as_ref()
             .expect("lexer_path must be specified before processing.");
-        if std::env::var("OUT_DIR").is_ok() {
-            println!("cargo:rerun-if-changed={}", lexerp.display());
-        }
         let outp = self
             .output_path
             .as_ref()

lrpar/src/lib/ctbuilder.rs

@@ -474,9 +474,6 @@ where
             .grammar_path
             .as_ref()
             .expect("grammar_path must be specified before processing.");
-        if std::env::var("OUT_DIR").is_ok() {
-            println!("cargo:rerun-if-changed={}", grmp.display());
-        }
         let outp = self
             .output_path
             .as_ref()