libuv: Allow windows UNC path with forward slashes

Fix libuv issue 3159 in CMake while integration in upstream libuv is
pending.

Fixes: #22141

Utilities/cmlibuv/src/win/process.c

@@ -169,7 +169,10 @@ static WCHAR* search_path_join_test(const WCHAR* dir,
                                     size_t cwd_len) {
   WCHAR *result, *result_pos;
   DWORD attrs;
-  if (dir_len > 2 && dir[0] == L'\\' && dir[1] == L'\\') {
+  if (
+    (dir_len > 2 && dir[0] == L'\\' && dir[1] == L'\\') ||
+    (dir_len > 2 && dir[0] == L'/' && dir[1] == L'/') 
+   ) {
     /* It's a UNC path so ignore cwd */
     cwd_len = 0;
   } else if (dir_len >= 1 && (dir[0] == L'/' || dir[0] == L'\\')) {