Error building www/firefox on amd64

[Paul Goyette <paul%whooppee.com@localhost>]

With pkgsrc updated to about 12 hours ago (2016-05-24 at 12:53:52 UTC) 
I'm seeing the following reproducible error with building firefox:

../config/nsinstall -R system_wrappers ../dist
../config/nsinstall: cannot access system_wrappers: No such file or directory
gmake[3]: *** [Makefile:65: export] Error 1
gmake[3]: Leaving directory '/tmp/pkgs/www/firefox/work.x86_64/build/config'
gmake[2]: *** [/tmp/pkgs/www/firefox/work.x86_64/firefox-46.0.1/config/recurse.mk:79: config/export] Error 2
gmake[2]: Leaving directory '/tmp/pkgs/www/firefox/work.x86_64/build'
gmake[1]: *** [/tmp/pkgs/www/firefox/work.x86_64/firefox-46.0.1/config/recurse.mk:33: export] Error 2
gmake[1]: Leaving directory '/tmp/pkgs/www/firefox/work.x86_64/build'
gmake: *** [/tmp/pkgs/www/firefox/work.x86_64/firefox-46.0.1/config/rules.mk:557: all] Error 2
*** Error code 2


+------------------+--------------------------+------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+------------------+--------------------------+------------------------+