Revert "dns cache per interface iteration 2"

This reverts commit f1464ff95670e6dcc0e12bf9fbbeb4c0346434c9

Change-Id: I3496b9a8cb54614fe3eea016d1391c8a89f3db38
diff --git a/libc/netbsd/resolv/res_state.c b/libc/netbsd/resolv/res_state.c
index efaa519..e05846a 100644
--- a/libc/netbsd/resolv/res_state.c
+++ b/libc/netbsd/resolv/res_state.c
@@ -50,7 +50,7 @@
 #endif
 
 static pthread_key_t   _res_key;
-static pthread_once_t  _res_once = PTHREAD_ONCE_INIT;
+static pthread_once_t  _res_once;
 
 typedef struct {
     int                  _h_errno;