verbs_usnic: add missing <stdio.h>

opal/mca/common/verbs_usnic/common_verbs_usnic_fake.c

@@ -38,6 +38,7 @@
 
 #include "opal_config.h"
 
+#include <stdio.h>
 #include <sys/types.h>
 #include <dirent.h>
 #include <string.h>