tests: suppressed a valgrind false positive in the latest nginx core.

Author: agentzh

valgrind.suppress

@@ -72,3 +72,12 @@ fun:main
    fun:do_preload
    fun:dl_main
 }
+{
+   <insert_a_suppression_name_here>
+   Memcheck:Leak
+   match-leak-kinds: definite
+   fun:malloc
+   fun:ngx_alloc
+   fun:ngx_set_environment
+   fun:ngx_single_process_cycle
+}