Use uv_sleep in the netmgr code

libuv added uv_sleep(unsigned int msec) to the API since 1.34.0.  Use that in
the netmgr code and define usleep based shim for libuv << 1.34.0.

configure.ac

@@ -600,7 +600,7 @@ LIBS="$LIBS $LIBUV_LIBS"
 
 # Those functions are only provided in newer versions of libuv, we'll be emulating them
 # for now
-AC_CHECK_FUNCS([uv_handle_get_data uv_handle_set_data uv_import uv_udp_connect uv_translate_sys_error])
+AC_CHECK_FUNCS([uv_handle_get_data uv_handle_set_data uv_import uv_udp_connect uv_translate_sys_error uv_sleep])
 AX_RESTORE_FLAGS([libuv])
 
 # libnghttp2

lib/isc/netmgr/netmgr.c

@@ -512,11 +512,7 @@ isc_nm_destroy(isc_nm_t **mgr0) {
 	 * Wait for the manager to be dereferenced elsewhere.
 	 */
 	while (isc_refcount_current(&mgr->references) > 1 && counter++ < 1000) {
-#ifdef WIN32
-		_sleep(10);
-#else  /* ifdef WIN32 */
-		usleep(10000);
-#endif /* ifdef WIN32 */
+		uv_sleep(10);
 	}
 
 #ifdef NETMGR_TRACE
@@ -531,11 +527,7 @@ isc_nm_destroy(isc_nm_t **mgr0) {
 	 * Now just patiently wait
 	 */
 	while (isc_refcount_current(&mgr->references) > 1) {
-#ifdef WIN32
-		_sleep(10);
-#else  /* ifdef WIN32 */
-		usleep(10000);
-#endif /* ifdef WIN32 */
+		uv_sleep(10);
 	}
 
 	/*

lib/isc/netmgr/uv-compat.h

@@ -33,6 +33,10 @@ uv_handle_set_data(uv_handle_t *handle, void *data) {
 }
 #endif /* ifndef HAVE_UV_HANDLE_SET_DATA */
 
+#ifndef HAVE_UV_SLEEP
+#define uv_sleep(msec) usleep(msec * 1000)
+#endif
+
 #ifdef HAVE_UV_UDP_CONNECT
 #define isc_uv_udp_connect uv_udp_connect
 #else