misc: Declare functions' prototype with no argument as `(void)`, not `()`
misc: Declare functions' prototype with no argument as `(void)`, not `()`

Not using the type in the function prototype parameter declaration can be
caught by "-Wstrict-prototypes". Avoid it, thus future build option changes
won't stop on it.

GNOME/evolution-mapi,GNOME/evolution-mapi