[CMake] add_custom_command dependencies in an auxiliary variable

[Rodolfo Lima]

Hi, I wonder if it's possible to add_custom_command create a temporary
variable which contents are all dependencies of the custom command. This
could be used if one command shall contain all dependencies in its
command line. gnu make does that with $^ (i think). Something similar
with the output file name would be good (like $@ in gnu-make).

Regards,
rod