Resolve __va_list_tag ** -> va_list * type errors with clang and future GCCs
Resolve __va_list_tag ** -> va_list * type errors with clang and future GCCs

Functions taking va_args are munged to receive arguments of type
'__va_list_tag *'. This patch uses va_copy to coerce them to the expected type
so we don't get compiler errors.

Tested on x86_64, both 32-bit and 64-bit compiles.

Reported-By: Basile Starynkevitch <e11bbaebd5e0efa08b433729e8f8e2e3f1a79fbd@starynkevitch.net>

akheron/jansson-debian,firepick1/FireSight,liu3tao/jansson,bstarynk/jansson,markalanj/jansson,chrullrich/jansson,gameclosure/jansson,npmccallum/jansson,simonfojtu/FireSight,simonfojtu/FireSight,rogerz/jansson,OlehKulykov/jansson,wirebirdlabs/featherweight-jansson,wirebirdlabs/featherweight-jansson,rogerz/jansson,firepick1/FireSight,simonfojtu/FireSight,rogerz/jansson,markalanj/jansson,attie/jansson,firepick1/jansson,firepick1/FireSight,Vorne/jansson,markalanj/jansson,rogerz/jansson,gameclosure/jansson,yahoo/ygloo-external-jansson,akheron/jansson,akheron/jansson-debian,yahoo/ygloo-external-jansson,akheron/jansson,AmesianX/jansson,attie/jansson,janetuk/jansson,firepick-delta/FireSight,akheron/jansson,firepick1/jansson,liu3tao/jansson,slackner/jansson,gameclosure/jansson,bstarynk/jansson,yahoo/ygloo-external-jansson,firepick-delta/FireSight,slackner/jansson,chrullrich/jansson,janetuk/jansson,firepick1/jansson,janetuk/jansson,AmesianX/jansson,akheron/jansson-debian,OlehKulykov/jansson,Mephistophiles/jansson,yahoo/ygloo-external-jansson,janetuk/jansson,firepick-delta/FireSight,Mephistophiles/jansson,bstarynk/jansson,Vorne/jansson,npmccallum/jansson,akheron/jansson-debian