Identify PEFile bitness without win32file

The Python win32file GetBinaryType API can't handle ARM64 binaries
because the underlying Windows GetBinaryType function knows nothing
about them. This change works around that by using pefile to extract the
information.

This will get mini_installer_tests past a current blocker.

Bug: 1431354
Change-Id: I92e2362ebf11566a4a894c6301e46d953e607fce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4455350
Reviewed-by: Robert Shield <[email protected]>
Reviewed-by: Alex Gough <[email protected]>
Commit-Queue: Robert Shield <[email protected]>
Auto-Submit: Bruce Dawson <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1134008}
diff --git a/third_party/pefile_py3/README.chromium b/third_party/pefile_py3/README.chromium
index 86587b9..85bea9e 100644
--- a/third_party/pefile_py3/README.chromium
+++ b/third_party/pefile_py3/README.chromium
@@ -14,4 +14,4 @@
 
 Local Modifications:
  - Only pefile.py, ordlookup, and LICENSE are present.
- - OWNERS and README.chromium files were added.
+ - BUILD.gn, OWNERS, and README.chromium files were added.