Adapt everything in BT5 to new capnhook API

This includes:
- Renaming of functions (iohook_invoke_next)
- Slight interface changes (com_proxy_wrap, iohook_push_handler)
- De-duplicate stuff from utils (iobuf, hr)

src/main/bsthook/acio.c

@@ -52,7 +52,7 @@ ac_io_bus_dispatch_irp(struct irp *irp)
     log_assert(irp != NULL);
 
     if (!ac_io_emu_match_irp(&ac_io_emu, irp)) {
-        return irp_invoke_next(irp);
+        return iohook_invoke_next(irp);
     }
 
     for (;;) {

src/main/bsthook/dllmain.c

@@ -20,10 +20,6 @@
 #include "util/defs.h"
 #include "util/log.h"
 
-static const irp_handler_t bsthook_handlers[] = {
-    ac_io_bus_dispatch_irp,
-};
-
 static bool my_dll_entry_init(char *sidcode, struct property_node *config);
 static bool my_dll_entry_main(void);
 
@@ -116,7 +112,7 @@ BOOL WINAPI DllMain(HMODULE self, DWORD reason, void *ctx)
     args_free(argc, argv);
 
     app_hook_init(my_dll_entry_init, my_dll_entry_main);
-    iohook_init(bsthook_handlers, lengthof(bsthook_handlers));
+    iohook_push_handler(ac_io_bus_dispatch_irp);
     rs232_hook_init();
 
     gfx_init();

src/main/bsthook/gfx.c

@@ -41,7 +41,7 @@ static HRESULT STDCALL my_CreateDevice(
     D3DPRESENT_PARAMETERS *pp,
     IDirect3DDevice9 **pdev)
 {
-    IDirect3D9 *real = COM_PROXY_UNWRAP(self);
+    IDirect3D9 *real = com_proxy_downcast(self)->real;
     HRESULT hr;
 
     log_misc("IDirect3D9::CreateDevice hook hit");
@@ -61,11 +61,17 @@ static IDirect3D9 *STDCALL my_Direct3DCreate9(UINT sdk_ver)
     IDirect3D9 *api;
     IDirect3D9Vtbl *api_vtbl;
     struct com_proxy *api_proxy;
+    HRESULT res;
 
     log_info("Direct3DCreate9 hook hit");
 
     api = real_Direct3DCreate9(sdk_ver);
-    api_proxy = com_proxy_wrap(api, sizeof(*api->lpVtbl));
+    res = com_proxy_wrap(&api_proxy, api, sizeof(*api->lpVtbl));
+
+    if (res != S_OK) {
+        log_fatal("Wrapping com proxy failed: 0x%ld", res);
+    }
+
     api_vtbl = api_proxy->vptr;
 
     api_vtbl->CreateDevice = my_CreateDevice;