Build History for pull/1103

Refactor Win32 blocking fd checks to use match guards

Add missing unix_waitpid_job stub for non-Windows platforms

Skip wait_read/wait_write on Windows for blocking fds On Windows, select() only works with socket handles, not with pipe handles or regular file handles. Calling wait_read or wait_write on a blocking pipe fd would fail because the underlying select() call cannot handle non-socket HANDLEs. Skip the wait_read/wait_write calls on Windows (guarded by Sys.win32) and let the worker thread handle blocking directly. This is safe because Sys.win32 is a compile-time constant, so there is no runtime overhead on Unix platforms. Affected call sites: read, pread, read_bigarray, write, pwrite, write_bigarray (6 total).