core: remove host_os and distname from message.cc

In message.cc there were const char* for host_os and distname that are
only meaningful for the debugger run during btraceback. As this doesn't
contain substantial information, this patch removes it.

core/scripts/btraceback.dbx

@@ -6,10 +6,7 @@ echo "exename ==> \c"; print -l (char *)exename
 echo "exepath ==> \c"; print -l (char *)exepath
 echo "catalog_db ==> \c"; print -l (char *)catalog_db
 echo "version ==> \c"; print -l (char *)version
-echo "host_os ==> \c"; print -l (char *)host_os
-echo "distname ==> \c"; print -l (char *)distname
 echo "distver ==> \c"; print -l (char *)distver
-echo "dist_name ==> \c"; print -l (char *)dist_name
 
 echo "******** RUNNING THREADS/LWPS:"
 echo

core/scripts/btraceback.gdb

@@ -4,11 +4,8 @@ print exepath
 print catalog_db
 print kBareosVersionStrings.FullWithDate
 print kBareosVersionStrings.BinaryInfo
-print host_os
-print distname
 print distver
 print host_name
-print dist_name
 show env TestName
 bt
 thread apply all bt

core/src/lib/message.cc

@@ -80,8 +80,6 @@ static bool trace = false;
 static bool hangup = false;
 
 /* Constants */
-const char* host_os = HOST_OS;
-const char* distname = DISTNAME;
 const char* distver = DISTVER;
 
 /*