__declspec(dllimport) isn't needed for linking to functions, extern
is sufficient. The preprocessor define used to determine when to
set it (_DLL) was incorrect, since that preprocessor define is set
anytime you're linking against dynamic CRT as opposed to static CRT.
Reviewed-by: Bill Kristiansen <billkris@Microsoft.com>
Reviewed-by: Marek Olák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12776>