98c38dc6d6
sets C99 as standard.
strdup() is not part of C99.
For now set `-D_POSIX_C_SOURCE=200809L` macro to have strdup() in C99.
Using `gnu99` instead would be another option.
We should take more care to use glib functions whenever possible.
Regards https://github.com/profanity-im/profanity/issues/1357
So far only with dummy value.
We will need an identifier that we can hash together with a message ID
and put in as the origin-id.
So when we receive message we can unsplit it and see if it was sent from
this client.
Regards https://github.com/profanity-im/profanity/issues/1207
