Extend the RunCMake.set_property test with cases covering buildsystem
target properties:
* COMPILE_DEFINITIONS
* COMPILE_FEATURES
* COMPILE_OPTIONS
* INCLUDE_DIRECTORIES
* LINK_LIBRARIES
* SOURCES
Also test a non-buildsystem property to document the current difference
in behavior. Refactor the existing LINK_LIBRARIES case to the same
more-extensive test as the rest. Use the output generated by CMake 3.3
as the expected output for each test case.
We use a special dedicated structure to store the LINK_LIBRARIES target
property. Do not try to construct a string from a NULL value. Instead
leave the property structure empty when no value is given.
Reported-by: Ghyslain Leclerc <ghleclerc@gmail.com>