Make checkout_rust in util/bot/DEPS also run hooks for clang

In 17164ff, it was asserted that checkout_rust did not need to actually
run util/bot/tools/clang/scripts/update.py, only to pull in the python
script.

This seems incorect after all, as bindgen must be able to find system
header files which it gets from libclang, so for consistency just run
the clang hook so that those header files are in a predictable location.

Change-Id: Ifc577d2847c5da2aa02f7a49b130243e599cb18c
Bug: 42290446
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/80787
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Auto-Submit: Lily Chen <chlily@google.com>

util/bot/DEPS

diff --git a/util/bot/DEPS b/util/bot/DEPS
index ec71eda..ae17bbc 100644
--- a/util/bot/DEPS
+++ b/util/bot/DEPS
@@ -199,7 +199,8 @@
   {
     'name': 'clang',
     'pattern': '.',
-    'condition': 'checkout_clang',
+    # bindgen in the packaged rust-toolchain requires packaged clang.
+    'condition': 'checkout_clang or checkout_rust',
     'action': [ 'python3',
                 'boringssl/util/bot/tools/clang/scripts/update.py',
                 '--output-dir', 'boringssl/util/bot/llvm-build',