all: use grep -E/-F instead of fgrep/egrep

egrep and fgrep are obsolescent now.

This PR updates all egrep and fgrep commands to grep -E and grep -F.
Running egrep/fgrep command with grep v3.8 will output the following warning to stderr:
egrep: warning: egrep is obsolescent; using grep -E

see also:
https://www.phoronix.com/news/GNU-Grep-3.8-Stop-egrep-fgrep
https://lists.gnu.org/archive/html/info-gnu/2022-09/msg00001.html

Change-Id: I0c6b6a039063d6aee94e8500971001996d4e498c
GitHub-Last-Rev: 1eee614
GitHub-Pull-Request: #137
Reviewed-on: https://go-review.googlesource.com/c/sys/+/432835
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

Author: kxxt

plan9/mkerrors.sh

@@ -126,7 +126,7 @@ errors=$(
 signals=$(
 	echo '#include <signal.h>' | $CC -x c - -E -dM $ccflags |
 	awk '$1=="#define" && $2 ~ /^SIG[A-Z0-9]+$/ { print $2 }' |
-	egrep -v '(SIGSTKSIZE|SIGSTKSZ|SIGRT)' |
+	grep -v 'SIGSTKSIZE\|SIGSTKSZ\|SIGRT' |
 	sort
 )
 
@@ -136,7 +136,7 @@ echo '#include <errno.h>' | $CC -x c - -E -dM $ccflags |
 	sort >_error.grep
 echo '#include <signal.h>' | $CC -x c - -E -dM $ccflags |
 	awk '$1=="#define" && $2 ~ /^SIG[A-Z0-9]+$/ { print "^\t" $2 "[ \t]*=" }' |
-	egrep -v '(SIGSTKSIZE|SIGSTKSZ|SIGRT)' |
+	grep -v 'SIGSTKSIZE\|SIGSTKSZ\|SIGRT' |
 	sort >_signal.grep
 
 echo '// mkerrors.sh' "$@"

unix/mkerrors.sh

@@ -642,7 +642,7 @@ errors=$(
 signals=$(
 	echo '#include <signal.h>' | $CC -x c - -E -dM $ccflags |
 	awk '$1=="#define" && $2 ~ /^SIG[A-Z0-9]+$/ { print $2 }' |
-	egrep -v '(SIGSTKSIZE|SIGSTKSZ|SIGRT|SIGMAX64)' |
+	grep -v 'SIGSTKSIZE\|SIGSTKSZ\|SIGRT\|SIGMAX64' |
 	sort
 )
 
@@ -652,7 +652,7 @@ echo '#include <errno.h>' | $CC -x c - -E -dM $ccflags |
 	sort >_error.grep
 echo '#include <signal.h>' | $CC -x c - -E -dM $ccflags |
 	awk '$1=="#define" && $2 ~ /^SIG[A-Z0-9]+$/ { print "^\t" $2 "[ \t]*=" }' |
-	egrep -v '(SIGSTKSIZE|SIGSTKSZ|SIGRT|SIGMAX64)' |
+	grep -v 'SIGSTKSIZE\|SIGSTKSZ\|SIGRT\|SIGMAX64' |
 	sort >_signal.grep
 
 echo '// mkerrors.sh' "$@"