Typo: lenghten->lengthen

Change-Id: I9b9e6afb543c42bf3b64cb3c2ed872304f33c7f0
Reviewed-on: https://gerrit.libreoffice.org/34282Reviewed-by: Julien Nabet <serval2412@yahoo.fr>
Tested-by: Julien Nabet <serval2412@yahoo.fr>

vcl/opengl/shaders/combinedVertexShader.glsl

@@ -40,7 +40,7 @@ void main()
 
    if (type == TYPE_LINE)
    {
-      // miter factor to additionally lenghten the distance of vertex (needed for miter)
+      // miter factor to additionally lengthen the distance of vertex (needed for miter)
       // if 1.0 - miter_factor has no effect
       float miter_factor = 1.0 / abs(extrusion_vectors.z);
       // fade factor is always -1.0 or 1.0 -> we transport that info together with length

vcl/opengl/shaders/lineVertexShader.glsl

@@ -20,7 +20,7 @@ uniform mat4 mvp;
 void main()
 {
    vec2 extrusion_vector = extrusion_vectors.xy;
-   // miter factor to additionally lenghten the distance of vertex (needed for miter)
+   // miter factor to additionally lengthen the distance of vertex (needed for miter)
    // if 1.0 - miter_factor has no effect
    float miter_factor = 1.0f / abs(extrusion_vectors.z);
    // fade factor is always -1.0 or 1.0 -> we transport that info together with length