Overflow exceptions missing when compiling with /ovf+

[cpyrgas]

There are no overflow exceptions thrown at runtime when numbers overflow by arithmetic operations, even if /ovf is enabled.

NOTE: Fixing this might cause problems in the X# runtime or user code that accidentally depends on this behavior. So we need to be very careful about fixing this and test a lot. Just logging it so it is not forgotten, but something to be looked at in the future, not now!!!

#pragma options (ovf,on)
#pragma options (fovf,on)
FUNCTION Start() AS VOID
	LOCAL dw AS DWORD
	LOCAL n AS INT

	dw := 1
	dw -= 2 // no exception
	? dw:ToString()
	n := Int32.MaxValue
	n ++  // no exception
	? n:ToString()
	
	// this one does thrown an overflow exception
//	n := -1
//	dw := (DWORD) n
	
	BEGIN CHECKED
		dw := 1
//		dw -= 2 // withing a CHECKED section, overflow exception does get thrown
	END CHECKED