clang-15: va_nvctrl.c hits Wdeprecated-non-prototype

[dvrogozh]

https://github.com/intel/libva/blob/0a989c9f0af69dcb15253945228c53780f019b79/va/x11/va_nvctrl.c#L133

See PR #619 which adds clang-15 coverage. Warning is:

va_nvctrl.c:133:12: warning: a function declaration without a prototype is deprecated in all versions of C and is treated as a zero-parameter prototype in C2x, conflicting with a subsequent definition [-Wdeprecated-non-prototype]
static int close_display();
           ^
va_nvctrl.c:153:36: note: conflicting prototype is here
static XEXT_GENERATE_CLOSE_DISPLAY(close_display, nvctrl_ext_info)