vcl opengl Windows: only log non-success wglMakeCurrent() failure reason

The rendering result on this Intel card is acceptable, but the console
is flooded with warnings saying wglMakeCurrent() failed with reason
"success", which makes it hard to see any other more important message.

I assume the root cause here is a broken driver.

Change-Id: I112279e9d669b804baeb47383b8357f1a1b7fde5
Reviewed-on: https://gerrit.libreoffice.org/54124Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

vcl/opengl/win/gdiimpl.cxx

@@ -114,7 +114,9 @@ void WinOpenGLContext::makeCurrent()
     if (!wglMakeCurrent(m_aGLWin.hDC, m_aGLWin.hRC))
     {
         g_bAnyCurrent = false;
-        SAL_WARN("vcl.opengl", "wglMakeCurrent failed: " << WindowsErrorString(GetLastError()));
+        DWORD nLastError = GetLastError();
+        if (nLastError != ERROR_SUCCESS)
+            SAL_WARN("vcl.opengl", "wglMakeCurrent failed: " << WindowsErrorString(nLastError));
         return;
     }