add static strvec initializer macradd static strvec initializer macroo

include/ucore/strvec.h

@@ -23,6 +23,10 @@ struct UCStrv
  */
 void uc_strv_init(struct UCStrv *strv);
 
+/** static initializer. Use as: struct UCStrv foo = UC_STRV_INITIALIZER;
+*/
+#define UC_STRV_INITIALIZER {0, 0, NULL}
+
 /**
  * Grow the UCStrv so it can hold n more items
  *