Fix several build failures with GCC6 due to unused static variables.

2015-09-18  Wilco Dijkstra  <wdijkstr@arm.com>

        * resolv/base64.c (rcsid): Remove unused static.
        * sysdeps/ieee754/dbl-64/atnat2.h (qpi1): Remove unused
        static.  (tqpi1): Likewise.
        * sysdeps/ieee754/dbl-64/uexp.h (one): Likewise.
        * sysdeps/ieee754/dbl-64/upow.h (sqrt_2): Likewise.
        * sysdeps/ieee754/flt-32/e_log10f.c (one): Likewise.
        * sysdeps/ieee754/flt-32/s_cosf.c (one): Likewise.
        * sysdeps/ieee754/ldbl-128/e_lgammal_r.c (zero): Likewise.
        * sysdeps/ieee754/ldbl-128/s_erfl.c (half): Likewise.
        * sysdeps/ieee754/ldbl-128/s_log1pl.c (maxlog): Likewise.
        * timezone/private.h (time_t_min): Likewise.  (time_t_max):
        Likewise.

(cherry picked from commit 6565fcb6)