Make mg_conn_addr_to_str return len

Also amend api_net.js to use returned length.

PUBLISHED_FROM=38e15f9587edf28049c5b9e5f126b4db159910e8

docs/c-api/util.h/mg_conn_addr_to_str.md

@@ -3,8 +3,8 @@ title: "mg_conn_addr_to_str()"
 decl_name: "mg_conn_addr_to_str"
 symbol_kind: "func"
 signature: |
-  void mg_conn_addr_to_str(struct mg_connection *nc, char *buf, size_t len,
-                           int flags);
+  int mg_conn_addr_to_str(struct mg_connection *c, char *buf, size_t len,
+                          int flags);
 ---
 
 Converts a connection's local or remote address into string.
@@ -17,5 +17,6 @@ see `MG_SOCK_STRINGIFY_*` definitions.
 - MG_SOCK_STRINGIFY_REMOTE - print remote peer's IP/port, not local address
 
 If both port number and IP address are printed, they are separated by `:`.
-If compiled with `-DMG_ENABLE_IPV6`, IPv6 addresses are supported. 
+If compiled with `-DMG_ENABLE_IPV6`, IPv6 addresses are supported.
+Return length of the stringified address. 
 

docs/c-api/util.h/mg_sock_addr_to_str.md

@@ -3,8 +3,8 @@ title: "mg_sock_addr_to_str()"
 decl_name: "mg_sock_addr_to_str"
 symbol_kind: "func"
 signature: |
-  void mg_sock_addr_to_str(const union socket_address *sa, char *buf, size_t len,
-                           int flags);
+  int mg_sock_addr_to_str(const union socket_address *sa, char *buf, size_t len,
+                          int flags);
 ---
 
 Convert the socket's address into string.