Source: Fix typo in _WIN32 preprocessor checks
Since CMake's default compiler flags with MSVC include -DWIN32
for
historical reasons, a few preprocessor conditions were accidentally
checking for WIN32
instead of _WIN32
. The corresponding blocks
were left out when compiling official binaries for cmake.org
because
we hard-code compiler flags without -DWIN32
.
Fixes: #22764 (closed)
Backport: release