crt: msvcr90d.def.in: Fix I386 symbol alias _wfindnext

Symbol redirects in import libraries are defined by "==", while
"=" in def files is used to rename a symbol on export, while
linking a DLL (but that does not have any effect when creating
an import library with dlltool).

Signed-off-by: Martin Storsjö <martin@martin.st>