Preserve substitution flag value within the current line.

Fixed the following testcase
# cat strings |./busybox sed -n -f test3.sed
1
1
2
c
c
# cat strings
a
b
c

1 files changed, 1 insertions, 1 deletions

diff --git a/editors/sed.c b/editors/sed.c
index aa3ce024e..2be4ed174 100644
--- a/editors/sed.c
+++ b/editors/sed.c
@@ -902,7 +902,7 @@ static void process_file(FILE * file)
                                 }
 #endif
                                         /* we print the pattern_space once, unless we were told to be quiet */
-                                        substituted = do_subst_command(sed_cmd, &pattern_space);
+                                        substituted |= do_subst_command(sed_cmd, &pattern_space);
 
 #ifdef CONFIG_FEATURE_SED_EMBEDED_NEWLINE
                                         /* undo HACK: escape newlines twice so regex can match them */