ntdll: Use ARRAY_SIZE instead of open coding it.

dlls/ntdll/unix/loader.c

@@ -635,7 +635,7 @@ static void init_paths( char *argv[] )
             static int pathname[] = { CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1 };
             size_t path_size = PATH_MAX;
             char *path = malloc( path_size );
-            if (path && !sysctl( pathname, sizeof(pathname)/sizeof(pathname[0]), path, &path_size, NULL, 0 ))
+            if (path && !sysctl( pathname, ARRAY_SIZE(pathname), path, &path_size, NULL, 0 ))
                 bin_dir = realpath_dirname( path );
             free( path );
         }