sync w/ upstream ksh.1 r1.152 and sh.1 r1.97

"Sun Aug 17 07:15:41 2014
update the built-ins list:
- "times" is both promoted to posix and special (ooh!)
- "pwd" is promoted to posix, but not special (aah!)

while here, jiggle the text somewhat to clarify that "non-POSIX"
actually meant when posix mode is off, not mandated by posix

joint work with guenther"

/jmc@/