pkg/48657: fontconfig can't find -lpng16 on multiple platforms for X11_TYPE=modular

[davshao%gmail.com@localhost]

>Number:         48657
>Category:       pkg
>Synopsis:       fontconfig can't find -lpng16 on multiple platforms for 
>X11_TYPE=modular
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Mar 14 06:25:00 +0000 2014
>Originator:     David Shao
>Release:        NetBSD 6.99.36 (GENERIC) amd64
>Organization:
>Environment:
NetBSD  6.99.36 NetBSD 6.99.36 (GENERIC) #1: Tue Mar 11 01:04:18 PDT 2014  
xxxxx@:/usr/obj/sys/arch/amd64/compile/GENERIC amd64

>Description:
On NetBSD 6.99.36, DragonFly 3.7-DEVELOPMENT i386 and x86_64 with 
X11_TYPE=modular, for latest cvs pkgsrc, (re)building fontconfig after
pkg_rolling-replace -uv
fails with

  CCLD     libfontconfig.la

*** Warning: linker path does not have real file for library -lpng16.
*** I have the capability to make that library automatically link in when
*** you link to this library.  But I can only do this if you have a
*** shared version of the library, which you do not appear to have
*** because I did check the linker path looking for a file starting
*** with libpng16 and none of the candidates passed a file format test
*** using a regex pattern. Last file checked: /usr/lib/libbz2.so
*** The inter-library dependencies that have been dropped here will be
*** automatically added whenever a program is linked with this library
*** or is declared to -dlopen it.

*** Since this library must not contain undefined symbols,
*** because either the platform does not support them or
*** it was explicitly requested with -no-undefined,
*** libtool will only create a static version of it.
  CC       fcarch.o
  CCLD     fcarch
gmake[3]: Leaving directory 
'/usr/pkgsrc/fonts/fontconfig/work/fontconfig-2.11.0/src'
gmake[2]: Leaving directory 
'/usr/pkgsrc/fonts/fontconfig/work/fontconfig-2.11.0/src'
Making all in fc-cache
gmake[2]: Entering directory 
'/usr/pkgsrc/fonts/fontconfig/work/fontconfig-2.11.0/fc-cache'
  CC       fc-cache.o
  CCLD     fc-cache
ld: cannot find -lpng16
Makefile:473: recipe for target 'fc-cache' failed
gmake[2]: *** [fc-cache] Error 1
gmake[2]: Leaving directory 
'/usr/pkgsrc/fonts/fontconfig/work/fontconfig-2.11.0/fc-cache'
Makefile:562: recipe for target 'all-recursive' failed
gmake[1]: *** [all-recursive] Error 1
gmake[1]: Leaving directory 
'/usr/pkgsrc/fonts/fontconfig/work/fontconfig-2.11.0'
Makefile:445: recipe for target 'all' failed
gmake: *** [all] Error 2
*** Error code 2

Stop.

on NetBSD 6.99.36, while on DragonFly there are explicit complaints about not 
being able to find -lpng16.

Could this be related to

Module Name:    pkgsrc
Date:           Thu Mar 13 23:26:35 UTC 2014

Modified Files:
        pkgsrc/graphics/freetype2: Makefile PLIST buildlink3.mk distinfo

>How-To-Repeat:

>Fix: