Use new-style system-id macros everywhere possible.  I hope I haven't
missed any.

This compiles and runs on Linux, and external applications have no
problems with it.  The definite test will be to build this on VMS.
diff --git a/apps/nseq.c b/apps/nseq.c
index 1d73d1a..93adcdf 100644
--- a/apps/nseq.c
+++ b/apps/nseq.c
@@ -121,7 +121,7 @@
 		}
 	} else {
 		out = BIO_new_fp(stdout, BIO_NOCLOSE);
-#ifdef VMS
+#ifdef OPENSSL_SYS_VMS
 		{
 		BIO *tmpbio = BIO_new(BIO_f_linebuffer());
 		out = BIO_push(tmpbio, out);