make all necessary structs public

vlib/builtin/map.v

@@ -6,7 +6,7 @@ module builtin
 
 import strings
 
-struct map {
+pub struct map {
 	element_size int
 	root      &mapnode
 pub:

vlib/builtin/string.v

@@ -43,7 +43,7 @@ NB: A V string should be/is immutable from the point of view of
 
 import strconv
 
-struct string {
+pub struct string {
 //mut:
 	//hash_cache int
 pub:
@@ -51,7 +51,7 @@ pub:
 	len int     // the length of the .str field, excluding the ending 0 byte. It is always equal to strlen(.str).
 }
 
-struct ustring {
+pub struct ustring {
 pub:
 	s     string
 	runes []int