Merge bitcoin/bitcoin#29774: build: Enable fuzz binary in MSVC

18fd522ca9 ci, msvc: Add "Run fuzz binaries" step (Hennadii Stepanov)
52933d7283 fuzz: Pass `SystemRoot` environment variable to subprocess (Hennadii Stepanov)
23cb8207cd ci, msvc: Add "Clone fuzz corpus" step (Hennadii Stepanov)
19dceddf4b build, msvc: Build `fuzz.exe` binary (Hennadii Stepanov)
4c078d7bd2 build, msvc: Enable preprocessor conformance mode (Hennadii Stepanov)
09f5a74198 fuzz: Re-implement `read_stdin` in portable way (Hennadii Stepanov)

Pull request description:

  Closes https://github.com/bitcoin/bitcoin/issues/29760.

  Suggested in https://github.com/bitcoin/bitcoin/pull/29758#issuecomment-2025593572.

ACKs for top commit:
  maflcko:
    lgtm ACK 18fd522ca9 🔍
  sipsorcery:
    tACK 18fd522ca9
  sipa:
    utACK 18fd522ca9

Tree-SHA512: 672ed6926ee9091f68f13780e77b60fc1d48731f16e847d849374f8426ffe1dafd9bcab06a27af62e8052ba345bb57f20f40579d6be8540c12ef85c23a6eec8b

test/fuzz/test_runner.py

@@ -11,6 +11,7 @@ import argparse
 import configparser
 import logging
 import os
+import platform
 import random
 import subprocess
 import sys
@@ -18,7 +19,7 @@ import sys
 
 def get_fuzz_env(*, target, source_dir):
     symbolizer = os.environ.get('LLVM_SYMBOLIZER_PATH', "/usr/bin/llvm-symbolizer")
-    return {
+    fuzz_env = {
         'FUZZ': target,
         'UBSAN_OPTIONS':
         f'suppressions={source_dir}/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1',
@@ -27,6 +28,10 @@ def get_fuzz_env(*, target, source_dir):
         'ASAN_SYMBOLIZER_PATH':symbolizer,
         'MSAN_SYMBOLIZER_PATH':symbolizer,
     }
+    if platform.system() == "Windows":
+        # On Windows, `env` option must include valid `SystemRoot`.
+        fuzz_env = {**fuzz_env, 'SystemRoot': os.environ.get('SystemRoot')}
+    return fuzz_env
 
 
 def main():