InFloat shader : Default to fetching "u"
InFloat shader : Default to fetching "u"

This provides compatibility for the recent Cortex UV naming change.

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