bug#57613: grep man page tries to rewrite POSIX history

[Geoff Clare]

The grep 3.8 man page at https://www.gnu.org/software/grep/manual/grep.html 
says, under "What happened to egrep and fgrep?":

egrep and fgrep were not standardized by POSIX

This is factually incorrect. They were included in POSIX.2-1992 but marked as 
obsolescent. When POSIX.2-1992 and POSIX.1-1996 were merged (along with the 
Single UNIX Specification) to form POSIX.1-2001, the obsolescent features from 
POSIX.2-1992 were removed.

Suggested fix - change:

egrep and fgrep were not standardized by POSIX and are no longer needed

to:

egrep and fgrep were marked obsolescent when they were standardized by POSIX in 
1992 and were removed in the 2001 revision; they have long been deprecated by 
GNU.

(I have it second hand that the GNU deprecation occurred in 2007; you could 
give that date instead of saying "long" if you can confirm it.)