configure: qemu-ga is only needed with softmmu targets

Remove it from the list of tools if --disable-system
and --disable-tools are used as we don't need it for
linux-user targets.
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
[lv: I also disable it with disable-tools, not only with disable-system]
Signed-off-by: NLaurent Vivier <lvivier@redhat.com>
Message-Id: <20190401141222.30034-4-lvivier@redhat.com>

configure

@@ -6079,7 +6079,9 @@ fi
 # Probe for guest agent support/options
 
 if [ "$guest_agent" != "no" ]; then
-  if [ "$linux" = "yes" -o "$bsd" = "yes" -o "$solaris" = "yes" -o "$mingw32" = "yes" ] ; then
+  if [ "$softmmu" = no -a "$want_tools" = no ] ; then
+      guest_agent=no
+  elif [ "$linux" = "yes" -o "$bsd" = "yes" -o "$solaris" = "yes" -o "$mingw32" = "yes" ] ; then
       tools="qemu-ga $tools"
       guest_agent=yes
   elif [ "$guest_agent" != yes ]; then