binary addons: only read the URL and revision of an addon if it is built
cmake: use separate_arguments() instead of string(REPLACE) to split a string into a list
binary addons: add platforms.txt to specify the platforms an addon can be built for
cmake: use ${CMAKE_COMMAND} instead of "cmake"
Merge pull request #5125 from Montellese/binary_addons_plat

binary addons: add platforms.txt to be able to control on which platforms an addon can be built