pkg/53832: textproc/sord-0.16.2 fails to build on NetBSD 7

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         53832
>Category:       pkg
>Synopsis:       textproc/sord-0.16.2 fails to build on NetBSD 7
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jan 04 14:40:00 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        NetBSD 7.2
>Organization:

>Environment:
System: NetBSD guava.gson.org 7.2 NetBSD 7.2 (GENERIC.201808291900Z) amd64
Architecture: x86_64
Machine: amd64
>Description:

Attempting to build textproc/sord on NetBSD 7.2 results in many
errors like these:

  [ 4/13] Compiling src/n3.c
  In file included from ../src/env.c:17:0:
  ../src/serd_internal.h: In function 'parse_counted_utf8_char':
  ../src/serd_internal.h:422:2: error: 'for' loop initial declarations are only allowed in C99 mode
    for (size_t i = 1; i < size; ++i) {
    ^
  ../src/serd_internal.h:422:2: note: use option -std=c99 or -std=gnu99 to compile your code
  ../src/serd_internal.h: In function 'uri_rooted_index':
  ../src/serd_internal.h:483:2: error: 'for' loop initial declarations are only allowed in C99 mode
    for (size_t i = 0; i < path_len && i < root_len; ++i) {
    ^

Adding c99 to USE_LANGUAGES does not help.

>How-To-Repeat:

>Fix: