Level 1 warnings are considered "severe" and, unsurprisingly, turning
them on revealed some true bugs.
- file-buffer.hpp: What should have been a zero extend followed by a
complement was instead a complement followed by a zero extend,
inadvertently truncating the file seek offset to 32 bits.
- file-map.cpp: What should have been a nullptr check after
CreateFileMapping() was instead a check for INVALID_HANDLE_VALUE. The
warning pointing me toward this was not technically about the misuse but
rather the redefinition of INVALID_HANDLE_VALUE in nall. I've removed
this and any reference to INVALID_HANDLE_VALUE except for error checks
immediately after calls to the few APIs that return it.
7faebad713