Rename some BUF_xxx to OPENSSL_xxx

Rename BUF_{strdup,strlcat,strlcpy,memdup,strndup,strnlen}
to OPENSSL_{strdup,strlcat,strlcpy,memdup,strndup,strnlen}
Add #define's for the old names.
Add CRYPTO_{memdup,strndup}, called by OPENSSL_{memdup,strndup} macros.

Reviewed-by: Tim Hudson <tjh@openssl.org>
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 571a891..efa0441 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -2577,7 +2577,7 @@
     if (!s->hit && tlsext_servername == 1) {
         if (s->tlsext_hostname) {
             if (s->session->tlsext_hostname == NULL) {
-                s->session->tlsext_hostname = BUF_strdup(s->tlsext_hostname);
+                s->session->tlsext_hostname = OPENSSL_strdup(s->tlsext_hostname);
                 if (!s->session->tlsext_hostname) {
                     *al = SSL_AD_UNRECOGNIZED_NAME;
                     return 0;