Pass -m32 when using clang-cl to build 32-bit runtimes

We already do it when bootstrapping, but should do it in general, so
that it works in non-bootstrapped builds with pinned clang as host
compiler (see bug).

Bug: 1013560
Change-Id: I37b3e1d8296b30602ea17364b131c26db490ce1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3656302
Commit-Queue: Arthur Eubanks <aeubanks@google.com>
Reviewed-by: Arthur Eubanks <aeubanks@google.com>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Auto-Submit: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1005826}
NOKEYCHECK=True
GitOrigin-RevId: fd53b43166f0ecb385bbed1ef480b8085705fb65
diff --git a/scripts/build.py b/scripts/build.py
index c0ecf12..3fc0b0e 100755
--- a/scripts/build.py
+++ b/scripts/build.py
@@ -1032,8 +1032,8 @@
       RmTree(compiler_rt_build_dir)
     os.makedirs(compiler_rt_build_dir)
     os.chdir(compiler_rt_build_dir)
-    if args.bootstrap:
-      # The bootstrap compiler produces 64-bit binaries by default.
+    if 'clang-cl' in cc:
+      # clang-cl produces 64-bit binaries by default.
       cflags += ['-m32']
       cxxflags += ['-m32']