sincos, sincosf, and sincosl implementation

[Steve Kargl]

For anyone who cares, I submitted a bugzilla report with
a patch of my implementations of sincos[fl].  I've had
this patch since 2011, so one might suspect that it has
been tested.  Immediate uses cases of these functions 
include improvements the Bessel and Neumann function family
of routines and possibly some of the complex trigometric
functions.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218300

-- 
Steve
20161221 https://www.youtube.com/watch?v=IbCHE-hONow