check if rdi path is writable before deciding to convert to it; if it isn't writable, then redirect to a rdi cache directory

src/http/http_stub.c

@@ -5,6 +5,7 @@
 //~ rjf: @per_os_impl Top-Level Layer Calls
 
 internal void http_init(void){}
+internal void http_async_tick(void){}
 
 ////////////////////////////////////////////////////////////////
 //~ rjf: @per_os_impl I/O Ring Functions