Clang: Re-package without the Fuchsia runtime on Darwin

The Fuchsia SDK is no longer provided for Mac in Chromium (see bug).

Bug: 1517393
Change-Id: I9efd1599ecc2829ca3dfa99bc2b592d4cb2b59ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5205252
Reviewed-by: Zequan Wu <zequanwu@google.com>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1249138}
NOKEYCHECK=True
GitOrigin-RevId: 3ac12bdbac03d6d85d2b0562cc786792512f941b
diff --git a/build_rust.py b/build_rust.py
index adf7218..4f44f0a 100755
--- a/build_rust.py
+++ b/build_rust.py
@@ -551,8 +551,6 @@
         if sys.platform.startswith('linux'):
             build_cmd.append('--without-android')
             build_cmd.append('--without-fuchsia')
-        if sys.platform == 'darwin':
-            build_cmd.append('--without-fuchsia')
         RunCommand(build_cmd + [
             '--build-dir', RUST_HOST_LLVM_BUILD_DIR, '--install-dir',
             RUST_HOST_LLVM_INSTALL_DIR