BUG #13500: Windows binary zip doesn't include libintl.h

The following bug has been logged on the website:

Bug reference:      13500
Logged by:          Kouhei Sutou
Email address:      kou@clear-code.com
PostgreSQL version: 9.4.4
Operating system:   Windows
Description:

//get.enterprisedb.com/postgresql/postgresql-9.4.2-1-windows-x64-binaries.zip
has pgsql\include\libintl.h but
//get.enterprisedb.com/postgresql/postgresql-9.4.4-1-windows-x64-binaries.zip
doesn't have it.

libintl.h is included from pgsql\include\server\c.h. The c.h is included
from pgsql\include\server\postgres.h.

I want to build an extension, PGroonga, for Windows with the official
PostgreSQL binary. But I get a build error caused by missing libintl.h.