maint: remove solar-time experiment

It occasionally causes confusion, e.g.,
<http://mm.icann.org/pipermail/tz/2013-November/020486.html>.
* Makefile (SDATA): Remove.  All uses removed.
* newctime.3 (NOTES): Remove reference to solar time.
* solar87, solar88, solar89: Remove.
* NEWS: Document this.
build: remove NOSOLAR option

The current tzdata now goes to 17, which is uncomfortably close to
the NOSOLAR limit of 20.
* Makefile (CFLAGS): Remove NOSOLAR comment.
* tzfile.h (TZ_MAX_TYPES): Ignore NOSOLAR; always default to 256.
* NEWS: Document this.