[core] add missing includes to quiet compiler warn

add missing system includes to quiet compiler warnings on Mac OS X

src/connections-glue.c

@@ -7,6 +7,7 @@
 #include "log.h"
 
 #include <errno.h>
+#include <string.h>
 
 const char *connection_get_state(connection_state_t state) {
 	switch (state) {

src/t/test_request.c

@@ -3,6 +3,7 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "base.h"
 #include "burl.h"