Remove WIN32-specific HAVE_ROUND-define
Remove WIN32-specific HAVE_ROUND-define

Remove the define HAVE_ROUND.

It was added as a workaround for _WIN32-builds to prevent conflicts
between pymath.h and math.h, but now the workaround caused a warning
instead.

lukas-ke/faint-graphics-editor,lukas-ke/faint-graphics-editor,lukas-ke/faint-graphics-editor,lukas-ke/faint-graphics-editor