Cannot build x11/libX11 in poudriere

[Anton Yuzhaninov]

I also can't build x11/libX11 in poudriere:

checking for X11... no
configure: error: Package requirements (xproto >= 7.0.17 xextproto
xtrans xcb >= 1.11.1 kbproto inputproto) were not met:

Package pthread-stubs was not found in the pkg-config search path.
Perhaps you should add the directory containing `pthread-stubs.pc'
to the PKG_CONFIG_PATH environment variable
Package 'pthread-stubs', required by 'xcb', not found

Is anybody working on this problem?