Use VERBATIM command arguments in cmake's add_custom_target
Use VERBATIM command arguments in cmake's add_custom_target

See #95 and comments to ab5a1981aa.

kapadia/vexcl,Poulpy21/vexcl,kapadia/vexcl,Poulpy21/vexcl,ddemidov/vexcl,ddemidov/vexcl,Poulpy21/vexcl