coverity#1358428 fix "Null pointer dereferences"

Change-Id: I629ff54ea721f4d9626258690767088b1abfb0c6
diff --git a/vcl/opengl/texture.cxx b/vcl/opengl/texture.cxx
index b3a3626..38ff8f7 100644
--- a/vcl/opengl/texture.cxx
+++ b/vcl/opengl/texture.cxx
@@ -398,11 +398,11 @@ void OpenGLTexture::FillCoords<GL_TRIANGLES>(std::vector<GLfloat>& aCoord, const
    GLfloat y1 = 0.0f;
    GLfloat y2 = 0.0f;

    double fTextureWidth(mpImpl->mnWidth);
    double fTextureHeight(mpImpl->mnHeight);

    if (mpImpl)
    {
        double fTextureWidth(mpImpl->mnWidth);
        double fTextureHeight(mpImpl->mnHeight);

        x1 = (maRect.Left() + rPosAry.mnSrcX) / fTextureWidth;
        x2 = (maRect.Left() + rPosAry.mnSrcX + rPosAry.mnSrcWidth) / fTextureWidth;