Small bug in c/unix/socket.c and parallel installation

Dear Scheme 48 developers,

In version 1.8 source file c/unix/socket.c, there's explicit use of
field h_addr of struct hostent, which is a deprecated alias of new
h_addr_list[0]. This alias is not always provided, and I suggest you
either replace the 2 occurrences of h_addr to h_addr_list[0] or accept
the patch I submit in the attachment.

Another issue is that there's a problem of make install in parallel,
say make -j3 install. The cause of this problem is that in serial,
directory $prefix/lib/scheme48-1.8 is first created and then binaries
like scheme48vm is copied there; however, if this process is performed
in parallel, this situation will occur:

A command like 'cp scheme48vm $prefix/lib/scheme48-1.8' is first
performed and then 'mkdir -p $prefix/lib/scheme48-1.8' will fail
because there's already a file $prefix/lib/scheme48-1.8.

So you should add some dependencies here.

Regards,
Charles