http: Check asprintf() return value
http: Check asprintf() return value

This fixes the following warning:

      CC       libopenconnect_la-http.lo
    http.c: In function 'openconnect_obtain_cookie':
    http.c:1270:13: warning: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Wunused-result]
         asprintf(&vpninfo->profile_url, "%s%s", bu, fu);
                 ^

Signed-off-by: Kevin Cernekee <3105dbb3dd63fbb4f6371cfb04adc6726f76c56b@gmail.com>
Signed-off-by: David Woodhouse <b460d66aaf00c296a3db1c1d9eeafc081d5f7d70@intel.com>

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