pkg/50753: pkg-config build failure with gcc6 defaults (linux)

[coypu%sdf.org@localhost]

>Number:         50753
>Category:       pkg
>Synopsis:       pkg-config build failure with gcc6 defaults (linux)
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Feb 03 00:00:00 +0000 2016
>Originator:     coypu
>Release:        pkgsrc-current
>Organization:
>Environment:
Linux localhost.localdomain 4.5.0-0.rc1.git2.1.fc24.x86_64 #1 SMP Fri Jan 29 18:55:50 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
>Description:
strftime expects third parameter to be a const char (this is true for NetBSD, too).

gdate.c:2497:7: error: format not a string literal, format string not checked [-Werror=format-nonliteral]
       tmplen = strftime (tmpbuf, tmpbufsize, locale_format, &tm);
       ^~~~~~


>How-To-Repeat:
build pkg-config or glib2 with -Werror=format-nonliteral
>Fix:
I've hacked it together with CFLAGS+=-Wno-error=format-nonliteral
the same exists for devel/glib2, too.

There is probably a better way to fix this.