+ provide for wide-characters as background character in wbkgrnd
(report/testcase by Anton Vidovic)
+ add name for Fedora's pcre2 to configure check for "--with-pcre2"
option, from xterm #363 -TD
+ modify adjustment in PutCharLR to restore the cursor position before
writing to the lower-right corner, rather than decrementing the
cursor column, in case it was a double-width character (cf: 20210130).