vcl: Fix possible memory leak in OpenGLSalBitmap

Fix possible memory leak in OpenGLSalBitmap::CreateTexture

Change-Id: Ic2d259569a5e89f60af7065b9d66ef03f82f90e7
Reviewed-on: https://gerrit.libreoffice.org/19049Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>

vcl/opengl/salbmp.cxx

@@ -447,6 +447,7 @@ GLuint OpenGLSalBitmap::CreateTexture()
 
                 pSrcData += mnBytesPerRow;
             }
+            delete pSrcFormat;
         }
     }