Configuration: fixed comments parsing.

Unclosed multi-line comments and "/" at the end of JSON shouldn't be allowed.

src/nxt_conf.c

@@ -1269,6 +1269,7 @@ nxt_conf_json_skip_space(u_char *start, u_char *end)
             case '\r':
                 continue;
             case '/':
+                start = p;
                 state = sw_after_slash;
                 continue;
             }
@@ -1285,7 +1286,6 @@ nxt_conf_json_skip_space(u_char *start, u_char *end)
                 continue;
             }
 
-            p--;
             break;
 
         case sw_single_comment:
@@ -1318,6 +1318,10 @@ nxt_conf_json_skip_space(u_char *start, u_char *end)
         break;
     }
 
+    if (nxt_slow_path(state != sw_normal)) {
+        return start;
+    }
+
     return p;
 }