as is done in the Windows headers.
Add #define COBJMACROS where needed in Wine.
Fixes the compilation of the oleaut32/tests/olefont.c and
urlmon/tests/url.c conformance tests with the Windows headers.
Implement DECIMAL, I8, UI8 types and other missing conversions.
VariantChangeType: Use LOCALE_USER_DEFAULT as per MSDN.
VariantChangeTypeEx: Support new types, pass proper flags.
VarNumFromParseNum: Support VT_DECIMAL as output.