Add mg_assemble_uri

PUBLISHED_FROM=533e134a48e0fca55509c3eb16b0a6b64c1188e8

docs/c-api/uri.h/intro.md

@@ -3,6 +3,7 @@ title: "URI"
 symbol_kind: "intro"
 decl_name: "uri.h"
 items:
+  - { name: mg_assemble_uri.md }
   - { name: mg_parse_uri.md }
 ---
 

docs/c-api/uri.h/mg_assemble_uri.md

@@ -0,0 +1,20 @@
+---
+title: "mg_assemble_uri()"
+decl_name: "mg_assemble_uri"
+symbol_kind: "func"
+signature: |
+  int mg_assemble_uri(const struct mg_str *scheme, const struct mg_str *user_info,
+                      const struct mg_str *host, unsigned int port,
+                      const struct mg_str *path, const struct mg_str *query,
+                      const struct mg_str *fragment, int normalize_path,
+                      struct mg_str *uri);
+---
+
+Assemble URI from parts. Any of the inputs can be NULL or zero-length mg_str.
+
+If normalize_path is true, path is normalized by resolving relative refs.
+
+Result is a heap-allocated string (uri->p must be free()d after use).
+
+Returns 0 on success, -1 on error. 
+