Write consensus files in binary mode

This will help us out on windows now that we mmap files.  Fixes part
of ticket 28614.

changes/ticket28614

@@ -0,0 +1,4 @@
+  o Major bugfixes (windows, startup):
+    - When writing a consensus file to disk, always write in
+      "binary" mode so that we can safely map it into memory later.
+      Fixes part bug 28614; bugfix on 0.4.0.1-alpha.

src/feature/nodelist/networkstatus.c

@@ -1991,7 +1991,7 @@ networkstatus_set_current_consensus(const char *consensus,
         waiting->set_at = now;
         waiting->dl_failed = 0;
         if (!from_cache) {
-          write_bytes_to_file(unverified_fname, consensus, consensus_len, 0);
+          write_bytes_to_file(unverified_fname, consensus, consensus_len, 1);
         }
         if (dl_certs)
           authority_certs_fetch_missing(c, now, source_dir);
@@ -2142,7 +2142,7 @@ networkstatus_set_current_consensus(const char *consensus,
   }
 
   if (!from_cache) {
-    write_bytes_to_file(consensus_fname, consensus, consensus_len, 0);
+    write_bytes_to_file(consensus_fname, consensus, consensus_len, 1);
   }
 
   warn_early_consensus(c, flavor, now);