testsuite: don't run grep NUL tests when we know the would fail

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/grep.tests

@@ -62,11 +62,13 @@ testing "grep -s nofile - (stdin and nonexisting file, match)" \
 	"grep -s domatch nonexistent - ; echo \$?" \
 	"(standard input):domatch\n2\n" "" "nomatch\ndomatch\nend\n"
 
+optional EXTRA_COMPAT
 testing "grep handles NUL in files" "grep -a foo input" "\0foo\n" "\0foo\n\n" ""
 testing "grep handles NUL on stdin" "grep -a foo" "\0foo\n" "" "\0foo\n\n"
 
 testing "grep matches NUL" "grep . input > /dev/null 2>&1 ; echo \$?" \
 	"0\n" "\0\n" ""
+SKIP=
 
 # -e regex
 testing "grep handles multiple regexps" "grep -e one -e two input ; echo \$?" \
@@ -84,11 +86,11 @@ testing "grep -E supports extended regexps" "grep -E fo+" "foo\n" "" \
 testing "grep is also egrep" "egrep foo" "foo\n" "" "foo\nbar\n"
 testing "egrep is not case insensitive" \
 	"egrep foo ; [ \$? -ne 0 ] && echo yes" "yes\n" "" "FOO\n"
-
 testing "grep -E -o prints all matches" \
 	"grep -E -o '([[:xdigit:]]{2}[:-]){5}[[:xdigit:]]{2}'" \
 	"00:19:3E:00:AA:5E\n00:1D:60:3D:3A:FB\n00:22:43:49:FB:AA\n" \
 	"" "00:19:3E:00:AA:5E 00:1D:60:3D:3A:FB 00:22:43:49:FB:AA\n"
+SKIP=
 
 testing "grep -o does not loop forever" \
 	'grep -o "[^/]*$"' \

testsuite/runtest

@@ -128,7 +128,7 @@ done
 export OPTIONFLAGS=:$(
 	sed -nr 's/^CONFIG_//p' "$bindir/.config" |
 	sed 's/=.*//' | xargs | sed 's/ /:/g'
-	)
+	):
 
 status=0
 for applet in $applets; do