This makes it a compile-time error to call a function that semantically
takes no parameters with a nonzero number of arguments.
Previously, such code would still compile, but risk blowing up the stack
if a compiler chose to use something other than caller-cleanup calling
conventions.
When input:grabKeyboardOnFocus is set (default), entering capture mode grabs
the keyboard a second time. This commit makes the second grab a no-op on
Wayland to avoid a crash.
