Fix gcc 4.1 compile error.
Fix gcc 4.1 compile error.

Note that only the AI_TYPE_FLOAT case was failing to compile, but it seemed like adding the other casts would be better for consistency.

ImageEngine/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,ivanimanishi/gaffer,hradec/gaffer,hradec/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,chippey/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,boberfly/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,hradec/gaffer,johnhaddon/gaffer,chippey/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,boberfly/gaffer,ivanimanishi/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,GafferHQ/gaffer,chippey/gaffer,appleseedhq/gaffer,chippey/gaffer,boberfly/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,boberfly/gaffer,ImageEngine/gaffer