sed: support \r in s command

function                                             old     new   delta
copy_parsing_escapes                                  65      91     +26

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

testsuite/sed.tests

@@ -287,6 +287,9 @@ testing "sed -i with address modifies all files, not only first" \
 	"cp input input2; sed -i -e '1s/foo/bar/' input input2 && cat input input2; rm input2" \
 	"bar\nbar\n" "foo\n" ""
 
+testing "sed understands \r" \
+	"sed 's/r/\r/'" \
+	"\rrr\n" "" "rrr\n"
 
 # testing "description" "arguments" "result" "infile" "stdin"