+ incorporate A_COLOR mask into COLOR_PAIR(), in case user application
provides an out-of-range pair number (report by Elijah Stone).
+ clarify description in tput manual page regarding support for
termcap names (prompted by FreeBSD #214709).
+ remove a restriction in tput's support for termcap names which
omitted capabilities normally not shown in termcap translations
(cf: 990123).
+ modify configure script for clang as used on FreeBSD, to work around
clang's differences in exit codes vs gcc.