Fix issue introduced in ba75bd16fef3ab461a7aeaa87af604875e04920a
Bug #58: Completed quoting for parameters of some CMake commands

A wiki article pointed out that whitespace will only be preserved for parameters
in CMake commands if passed strings will be appropriately quoted or escaped.
http://cmake.org/Wiki/CMake/Language_Syntax#CMake_splits_arguments_unless_you_use_quotation_marks_or_escapes.

Quoting was added so that more places should also handle file names correctly
which contain space characters or semicolons eventually.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>