Adapt bf_lbuf for opaque BIO

Also, have it always be built, even though it's only (currently) used
on VMS.  That will assure it will get the same changes as all others.
Reviewed-by: NMatt Caswell <matt@openssl.org>

crypto/bio/bf_lbuf.c

@@ -57,8 +57,8 @@
 
 #include <stdio.h>
 #include <errno.h>
+#include "bio_lcl.h"
 #include "internal/cryptlib.h"
-#include <openssl/bio.h>
 #include <openssl/evp.h>
 
 static int linebuffer_write(BIO *h, const char *buf, int num);

crypto/bio/build.info

@@ -5,5 +5,4 @@ SOURCE[../../libcrypto]=\
         bss_file.c bss_sock.c bss_conn.c \
         bf_null.c bf_buff.c b_print.c b_dump.c b_addr.c \
         b_sock.c b_sock2.c bss_acpt.c bf_nbio.c bss_log.c bss_bio.c \
-        bss_dgram.c bio_meth.c \
-        {- $config{target} =~ /^VMS/i ? "bf_lbuf.c" : "" -}
+        bss_dgram.c bio_meth.c bf_lbuf.c