Encapsulate the asn1c call from cmake in a cmake function run_asn1c().
As a notable change to the previous manual add_custom_command()
invocation, in suppresses the output of asn1c by default [1] and stores
it in a log file. In case of asn1c4 error, the output will output on
stdout.
Use the new run_asn1c() in all occasions for code generation.
[1] it is quite verbose, with many warnings that we cannot influence nor
suppress, and lists all generated files which is verified by the build
system automatically, anyway.
Robert Schmidt
05d393a399