Avoid pollution from ares.h into the global space.

src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver.h

@@ -34,8 +34,6 @@
 #ifndef GRPC_CORE_EXT_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H
 #define GRPC_CORE_EXT_RESOLVER_DNS_C_ARES_GRPC_ARES_EV_DRIVER_H
 
-#include <ares.h>
-
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/iomgr/pollset_set.h"
 

src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver_posix.c

@@ -34,6 +34,8 @@
 #include "src/core/lib/iomgr/port.h"
 #if GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET)
 
+#include <ares.h>
+
 #include "src/core/ext/resolver/dns/c_ares/grpc_ares_ev_driver.h"
 
 #include <grpc/support/alloc.h>