Fix compile error: this function declaration is not a prototype

`cef_basetime_now()` failed to compile if `-Wstrict-prototypes` is set in clang
or gcc.

include/internal/cef_time.h

@@ -122,7 +122,7 @@ CEF_EXPORT int cef_time_now(cef_time_t* cef_time);
 ///
 /// Retrieve the current system time.
 ///
-CEF_EXPORT cef_basetime_t cef_basetime_now();
+CEF_EXPORT cef_basetime_t cef_basetime_now(void);
 
 ///
 /// Retrieve the delta in milliseconds between two time values. Returns true (1)