Fix minor oops (removed #include<string.h> erroneously)

httperf/src/conn.c

@@ -37,6 +37,7 @@
 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include <generic_types.h>
 #include <object.h>

httperf/src/core.c

@@ -42,6 +42,7 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #include <sys/ioctl.h>