[COMMITTED] Fix GCC6 build errors due to unused statics

[Joseph Myers]

On Fri, 18 Sep 2015, Wilco Dijkstra wrote:

> 	* timezone/private.h (time_t_min): Likewise.  (time_t_max):
> 	Likewise.

The timezone/ code is imported verbatim from upstream tzcode releases and 
should not be changed locally.  Please revert this change and work with 
Paul on getting a fix into upstream tzcode.  When there's a new tzcode 
release, you can then import it into glibc.  (Some Makefile changes will 
be needed as part of the import of new code; see 
<https://sourceware.org/ml/libc-alpha/2015-05/msg00553.html>.  Do not try 
to combine this with importing a new version of tzdata.)

-- 
Joseph S. Myers
joseph@codesourcery.com