winhttp: Add a stub for WinHttpOpen.

dlls/winhttp/main.c

@@ -114,3 +114,18 @@ BOOL WINAPI WinHttpGetIEProxyConfigForCurrentUser(WINHTTP_CURRENT_USER_IE_PROXY_
     SetLastError(ERROR_SUCCESS);
     return TRUE;
 }
+
+/***********************************************************************
+ *          WinHttpOpen (winhttp.@)
+ */
+HINTERNET WINAPI WinHttpOpen(LPCWSTR pwszUserAgent, DWORD dwAccessType,
+                             LPCWSTR pwszProxyName, LPCWSTR pwszProxyByPass,
+                             DWORD dwFlags)
+{
+    FIXME("(%s, %d, %s, %s, 0x%x): stub\n", debugstr_w(pwszUserAgent),
+        dwAccessType, debugstr_w(pwszProxyName), debugstr_w(pwszProxyByPass),
+        dwFlags);
+
+    SetLastError(ERROR_NOT_SUPPORTED);
+    return NULL;
+}

dlls/winhttp/winhttp.spec

@@ -12,7 +12,7 @@
 @ stub WinHttpGetDefaultProxyConfiguration
 @ stdcall WinHttpGetIEProxyConfigForCurrentUser(ptr)
 @ stub WinHttpGetProxyForUrl
-@ stub WinHttpOpen
+@ stdcall WinHttpOpen(wstr long wstr wstr long)
 @ stub WinHttpOpenRequest
 @ stub WinHttpQueryAuthSchemes
 @ stub WinHttpQueryDataAvailable