ValuePlug: Added support for Houdini17.5
ValuePlug: Added support for Houdini17.5

Compiler options for Houdini17.5 makes it complain about
the const qualifier already in the declaration and not necessary in the
definition.

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