build-sys: fix make distcheck
build-sys: fix make distcheck

- Do not refer to .c files managed by another makefile (this will fail
  make distclean)
- Do not refer to files by relative path (should use $top_srcdir for ex)
- Use LDADD for object linking instead of LDFLAGS, for linker flags

alon/spice-server,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,freedesktop-unofficial-mirror/spice__spice,alon/spice-server,mathslinux/spice,elmarco/spice,ya-mouse/spice,fgouget/spice,mathslinux/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,dezelin/spice,dezelin/spice,SPICE/spice,dezelin/spice,Fantu/spice,elmarco/spice,SPICE/spice,ya-mouse/spice,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,alon/spice-server,Fantu/spice,fgouget/spice,ya-mouse/spice,dezelin/spice,alon/spice-server,mathslinux/spice,Fantu/spice,freedesktop-unofficial-mirror/spice__spice,alon/spice-server,fgouget/spice,fgouget/spice,Fantu/spice,SPICE/spice,elmarco/spice,dezelin/spice,elmarco/spice