-DFREEIMAGE_LIB prevents dynamic linking to FreeImage

I'm cross-compiling OGRE for win32 with gcc 4.4.2.

The attached patch removes the -DFREEIMAGE_LIB pre-processor flag, which prevents dynamically linking to FreeImage.

I don't know if you intend to support dynamically linking to FreeImage, hence the low severity of the bug.

I'm afraid I'm not yet familiar enough with CMake to provide a patch that makes the definition depend on whether the user wants to link statically or dynamically. If FREEIMAGE_LIB is not required for static linking then it might be best to remove it altogether.

Do you know what the other -D options on the line I changed are for? The commit message that introduced them merely says "introduce new Cmake build system". Commenting their purpose would be appreciated.

Original Mantis Ticket: http://www.ogre3d.org/mantis/view.php?id=280