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_ext.c b/ssl/t1_ext.c
index 396ad7e..2ffe271 100644
--- a/ssl/t1_ext.c
+++ b/ssl/t1_ext.c
@@ -183,7 +183,7 @@
 {
     if (src->meths_count) {
         dst->meths =
-            BUF_memdup(src->meths,
+            OPENSSL_memdup(src->meths,
                        sizeof(custom_ext_method) * src->meths_count);
         if (dst->meths == NULL)
             return 0;