It is outdated and no longer effectively used. It was originally in
place to prevent rebuilding generated files (from a tarball) if the
right build tools (awk, Perl, indent) were not available. However, we no
longer use indent, we have hard-required awk for a while, and the only
places the @REBUILD@ substitution was still used were for
glib-genmarshal, which has recently been rewritten in Python (so no
longer depends on whether Perl is available).
Drop the whole lot.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://bugzilla.gnome.org/show_bug.cgi?id=694723