Fixed bug in the s_header_value state

If the buffer ended with the '\r' char on the s_header_value state, the parser triggered the on_header_value() callback twice (buffer="data\r"): 1st time with "data" and 2nd time "data\r" resulting in "datadata\r" instead of "data".

multipart_parser.c

@@ -199,6 +199,7 @@ size_t multipart_parser_execute(multipart_parser* p, const char *buf, size_t len
         if (c == CR) {
           EMIT_DATA_CB(header_value, buf + mark, i - mark);
           p->state = s_header_value_almost_done;
+          break;
         }
         if (is_last)
             EMIT_DATA_CB(header_value, buf + mark, (i - mark) + 1);