[4.1] 987ea3c Only the cli thread can send events to backends

[Dridi Boukelmoune]

commit 987ea3c1040132d89da9ce2b7801679af061f537
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Sun Aug 23 12:25:27 2015 +0200

    Only the cli thread can send events to backends

diff --git a/bin/varnishd/cache/cache_vcl.c b/bin/varnishd/cache/cache_vcl.c
index 7e6247b..139e18b 100644
--- a/bin/varnishd/cache/cache_vcl.c
+++ b/bin/varnishd/cache/cache_vcl.c
@@ -229,6 +229,7 @@ vcl_BackendEvent(const struct vcl *vcl, enum vcl_event_e e)
 {
 	struct backend *be;
 
+	ASSERT_CLI();
 	CHECK_OBJ_NOTNULL(vcl, VCL_MAGIC);
 	AZ(vcl->busy);