set_source_files_properties
---------------------------

Source files can have properties that affect how they are built.

::

  set_source_files_properties([file1 [file2 [...]]]
                              PROPERTIES prop1 value1
                              [prop2 value2 [...]])

Set properties associated with source files using a key/value paired
list.  See properties documentation for those known to CMake.
Unrecognized properties are ignored.  Source file properties are
visible only to targets added in the same directory (CMakeLists.txt).
