Remove the BINDGEN_RS_FILE env var from boringssl build rules

BoringSSL no longer uses the env var in Chromium, so this can
be dropped. It now uses OUT_DIR/bindgen.rs.

Also drop the visibility of the generated rs file from outside
the copy rule. 1p code should use rust_bindgen which depends on
the copy and thus transitively depends on the generation step.

R=davidben@chromium.org

Bug: b/373864033
Change-Id: I51e4339ce4cad8d6beba5141bb3b0d099b9fe04a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5979353
Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Mohannad Farrag <aymanm@google.com>
Cr-Commit-Position: refs/heads/main@{#1376267}
NOKEYCHECK=True
GitOrigin-RevId: 77a3722b16235d5956adc712d9424070b1950a95
diff --git a/BUILD.gn b/BUILD.gn
index 94fdb1c..12b2fb6 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -79,7 +79,6 @@
     edition = "2021"
     deps = [
       ":boringssl",
-      ":raw_bssl_sys_bindings",  # Delete once the source code has changed.
       ":raw_bssl_sys_bindings_static_fns",
     ]
 
@@ -88,14 +87,6 @@
     ]
 
     bindgen_deps = [ ":raw_bssl_sys_bindings" ]
-
-    # This is no longer necessary and can be deleted once the source
-    # code is changed to use `OUT_DIR` always.
-    bindgen_output = get_target_outputs(":raw_bssl_sys_bindings")
-    inputs = bindgen_output
-    rustenv =
-        [ "BINDGEN_RS_FILE=" +
-          rebase_path(bindgen_output[0], get_path_info(crate_root, "dir")) ]
   }
 
   # Rust bindings to boringssl