bootstrap: Compile with _FILE_OFFSET_BITS=64 on Linux
To avoid problems accessing filesystem, explicitly use 64-bit file offsets in case the compilation model is 32-bit. This change was made for the main CMake build by !5258 (merged), but conditionally on 32-bit Linux. For bootstrap, just always add the definition instead of trying to detect the architecture.
Fixes: #22328 (closed)