libarchive @3.3.1 fails to build on Snow Leopard (10.6.8)

[Ryan Schmidt]

> On Mar 4, 2017, at 10:39, Richard L. Hamilton <rlhamil at smart.net> wrote:
> 
> libarchive/archive_read_disk_entry_from_file.c:677: error: ‘ACL_SYNCHRONIZE’ undeclared here (not in a function)
> 
> What it boils down to is that the source is now using a symbol that was not defined in Snow Leopard (without checking for its availability).
> 
> Since it looks like it's making no decisions with that, but merely using it as part of a group of attributes to use when constructing a "trivial NFSv4 ACL from mode", some #ifdefs could probably work around it being present or absent.
> 
> <main.log-libarchive.txt.gz>

See https://trac.macports.org/ticket/53712