vtcp: Ignore EINTR with sanitizers

Technically it can also happen with a debugger attached to a process
despite SA_RESTART.

lib/libvarnish/vtcp.c

@@ -600,6 +600,10 @@ VTCP_Check(ssize_t a)
 	 */
 	if (errno == EINVAL)
 		return (1);
+#endif
+#if (defined(__SANITIZER) || __has_feature(address_sanitizer))
+	if (errno == EINTR)
+		return (1);
 #endif
 	return (0);
 }