util: add a return value to util_sprintf

The regular sprintf is expected to return the number of char writter,
so let's do the same in our version.

Reviewed-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20643>

src/util/u_string.h

@@ -67,14 +67,15 @@ util_strchrnul(const char *s, char c)
 #ifdef _WIN32
 
 #define sprintf util_sprintf
-static inline void
+static inline int
    PRINTFLIKE(2, 3)
 util_sprintf(char *str, const char *format, ...)
 {
    va_list ap;
    va_start(ap, format);
-   vsnprintf(str, INT_MAX, format, ap);
+   int r = vsnprintf(str, INT_MAX, format, ap);
    va_end(ap);
+   return r;
 }
 
 #define vasprintf util_vasprintf