+ correct a check made in lib_napms.c, so that terminfo applications
can again use napms() (cf: 20110604).
+ add a note in tic.h regarding required casts for ABSENT_BOOLEAN
(cf: 20040327).
+ correct scripting for --disable-echo option in test/configure.
+ amend check for missing c++ compiler to work when no error is
reported, and no variables set (cf: 20021206).
+ add/use configure macro CF_DISABLE_ECHO.