* Fix possible C2084 compiler error
Guiddef.h uses a separate header guard to define the GUID operators, in the current codebase this won't cause any issue, but i got such error while fiddling a bit with the program and including something that ended up including all the various windows headers, that ended up including Guiddef.h, causing the error as by not finding the macro declared, it ended up declaring the inline operators as well.
* Update api.h
* [EAX] Use separate FX slot state for each version
[EAX] Don't defer FX slot properties
* [EAX_FXSLOT] Use mPropsDirty to defer update
[EAX_CONTEXT] Commit all updates on first initialization
Even though it's only a single value, this allows for not having to explicitly
track version changes, since the version being changed to will always have a
property change, implicitly marking an EAX update/commit for the source.
