pkg/50377: net/ntp4 build fails on NetBSD 6.1.5

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

>Number:         50377
>Category:       pkg
>Synopsis:       net/ntp4 build fails on NetBSD 6.1.5
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Oct 29 09:10:00 +0000 2015
>Originator:     Andreas Gustafsson
>Release:        NetBSD 6.1.5
>Organization:

>Environment:
System: NetBSD guava.gson.org 6.1.5 NetBSD 6.1.5 (GENERIC) amd64
Architecture: x86_64
Machine: amd64
>Description:

When I try to build ntp-4.2.8p3 from pkgsrc on NetBSD/amd64 6.1.5,
it fails with:

   --- ntpd ---
     CCLD     ntpd
   ntpd.o: In function `ntpdmain':
   ntpd.c:(.text.ntpdmain+0x2c): undefined reference to `pthread_create'
   ntpd.c:(.text.ntpdmain+0x74c): undefined reference to `pthread_cancel'
   ntpd.c:(.text.ntpdmain+0x75b): undefined reference to `pthread_join'
   ld generated: undefined reference to `pthread_cancel'
   *** [ntpd] Error code 1

>How-To-Repeat:

>Fix: