Take advantage of groff's AD string and HY register

Fixes https://gitlab.com/man-db/man-db/-/issues/23.  Thanks to G.
Branden Robinson for assistance.

* src/man.c (make_roff_command) [TROFF_IS_GROFF]: Implement
`--no-hyphenation` using `-rHY=0`.  This requires groff >= 1.19,
released in 2003.
(disable_hyphenation): Only define if `TROFF_IS_GROFF` is not defined.
(display): Only use the more complex hyphenation-control mechanism if
`TROFF_IS_GROFF` is not defined.

* src/man.c (disable_justification): Implement using `.ds AD l` if groff
is at least version 1.23.0.
(display): Adjust debugging output to reflect this (more or less).

* NEWS.md: Document this.

1 files changed, 2 insertions, 0 deletions

diff --git a/NEWS.md b/NEWS.md
index 2c3f1aa5..37d9df7c 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -20,6 +20,8 @@ Improvements:
  * Add a `STANDARDS` section to `man(1)` itself.
  * Document that `man -K` may suffer from false negatives as well as false
    positives.
+ * Take advantage of newer `groff` facilities to implement `man
+   --no-hyphenation` and `man --no-justification`, if available.
 
 man-db 2.11.2 (8 January 2023)
 ==============================