Include <errno.h> in xml.c to fix non-libstoken build
Include <errno.h> in xml.c to fix non-libstoken build

Pointed out by Nikos Mavrogiannopoulos.

Signed-off-by: David Woodhouse <b460d66aaf00c296a3db1c1d9eeafc081d5f7d70@intel.com>

brandt/openconnect,mtmiller/openconnect,atyndall/openconnect,liiir1985/openconnect,matlockx/openconnect,brandt/openconnect,matlockx/openconnect,nmav/openconnect-mine,brandt/openconnect,matlockx/openconnect,cernekee/openconnect,matlockx/openconnect,cernekee/openconnect,chadcatlett/openconnect,mveplus/openconnect-client,neshema/openconnect,liiir1985/openconnect,nmav/openconnect-mine,mtmiller/openconnect,chadcatlett/openconnect,nmav/openconnect-mine,neshema/openconnect,cernekee/openconnect,neshema/openconnect,chadcatlett/openconnect,mtmiller/openconnect,mtmiller/openconnect,don-johnny/openconnect,atyndall/openconnect,don-johnny/openconnect,lins05/openconnect,mveplus/openconnect-client,lins05/openconnect,don-johnny/openconnect,liiir1985/openconnect,brandt/openconnect,liiir1985/openconnect,mveplus/openconnect-client,lins05/openconnect,cernekee/openconnect,chadcatlett/openconnect,lins05/openconnect,atyndall/openconnect,atyndall/openconnect,neshema/openconnect,nmav/openconnect-mine,mveplus/openconnect-client,don-johnny/openconnect