[clang] Build clang with pinned clang on all platforms

Followup to https://crrev.com/c/3572241.

We can't use NamedTemporaryFile on Windows (can't read from it while having a handle to it): https://docs.python.org/3.9/library/tempfile.html. Use a consistent path for the pinned update.py instead.

Bug: 1010466, 1013560
Change-Id: Ibaa0e7d2e9789ac24a852f3c7083a59cb242e793
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3590911
Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Arthur Eubanks <aeubanks@google.com>
Cr-Commit-Position: refs/heads/main@{#997580}
NOKEYCHECK=True
GitOrigin-RevId: e4598f8d5c0b63528f3b1450aaeafcefe2ddd8ad
2 files changed