Windows: Fallback to checking registry if port is not CHAR/UNKNOWN

Some devices, e.g. a uBlox is incorrectly registered in Windows as a file device. This prevents the port from being opened. In this case, check as a last resort that the port exists in the registry. If so, then open it anyway.

Issue: jcurl#64, DOTNET-169

code/Native/WinNativeSerial.cs

@@ -843,10 +843,27 @@ public void Open()
             if (m_ComPortHandle.IsInvalid) WinIOError();
 
             NativeMethods.FileType t = UnsafeNativeMethods.GetFileType(m_ComPortHandle);
+            bool validOverride = false;
             if (t != NativeMethods.FileType.FILE_TYPE_CHAR && t != NativeMethods.FileType.FILE_TYPE_UNKNOWN) {
-                m_ComPortHandle.Dispose();
-                m_ComPortHandle = null;
-                throw new IOException("Wrong file type: " + PortName);
+                foreach (string port in GetPortNames()) {
+#if NETSTANDARD15
+                    if (port.Equals(PortName, StringComparison.OrdinalIgnoreCase)) {
+                        validOverride = true;
+                        break;
+                    }
+#else
+                    if (port.Equals(PortName, StringComparison.InvariantCultureIgnoreCase)) {
+                        validOverride = true;
+                        break;
+                    }
+#endif
+                }
+
+                if (!validOverride) {
+                    m_ComPortHandle.Dispose();
+                    m_ComPortHandle = null;
+                    throw new IOException("Wrong file type: " + PortName);
+                }
             }
 
             // Set the default parameters