Fix build by commit 072965eb0 for modules:
EXPLORER, COMCTL32, IERNONCE, URLMON, USER32_(API|WINE)TESTS
Note that some of these modules (from Wine) already have the OEMRESOURCE
defined; however, only in one of their files. But we have added
precompiled headers for them where we have included either windows.h
or winuser.h in them, without OEMRESOURCE. The result is, that when
compiling these modules with PCH support, the OEMRESOURCE define was
_not_ satisfied and thus, compile errors arose.
Fix this by adding #define OEMRESOURCE before the windows headers also
in the precompiled headers we have added for these modules.
