ares__bitncmp: use two underscores for private functions

It used a single one previously making it look like a public one

ares_gethostbyname.c

@@ -460,7 +460,7 @@ static int get_address_index(const struct in_addr *addr,
         }
       else
         {
-          if (!ares_bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr,
+          if (!ares__bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr,
                              sortlist[i].mask.bits))
             break;
         }
@@ -508,9 +508,7 @@ static int get6_address_index(const struct ares_in6_addr *addr,
     {
       if (sortlist[i].family != AF_INET6)
         continue;
-        if (!ares_bitncmp(addr,
-                          &sortlist[i].addrV6,
-                          sortlist[i].mask.bits))
+      if (!ares__bitncmp(addr, &sortlist[i].addrV6, sortlist[i].mask.bits))
         break;
     }
   return i;

bitncmp.c

@@ -33,8 +33,8 @@
  * author:
  *	Paul Vixie (ISC), June 1996
  */
-int
-ares_bitncmp(const void *l, const void *r, int n) {
+int ares__bitncmp(const void *l, const void *r, int n)
+{
   unsigned int lb, rb;
   int x, b;
 

bitncmp.h

@@ -2,7 +2,7 @@
 #define __ARES_BITNCMP_H
 
 
-/* Copyright (C) 2005 by Dominick Meglio
+/* Copyright (C) 2005, 2013 by Dominick Meglio
  *
  * Permission to use, copy, modify, and distribute this
  * software and its documentation for any purpose and without
@@ -18,9 +18,9 @@
  */
 
 #ifndef HAVE_BITNCMP
-int ares_bitncmp(const void *l, const void *r, int n);
+int ares__bitncmp(const void *l, const void *r, int n);
 #else
-#define ares_bitncmp(x,y,z) bitncmp(x,y,z)
+#define ares__bitncmp(x,y,z) bitncmp(x,y,z)
 #endif
 
 #endif /* __ARES_BITNCMP_H */