Using a pragma instead of guards is easier to write, less error prone
and avoids name clashes (a source of very subtle bugs). This pragma
is supported on almost all compilers, including all the compilers we
care about: https://en.wikipedia.org/wiki/Pragma_once#Portability.
This patch does not change the autogenerated files: asn1/asn1c/*.h.
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>
