libbb: introduce fputc_printable (from ed)

netstat: print control chars as ^C etc
vi: style fixlet

function                                             old     new   delta
fputc_printable                                        -     100    +100
unix_do_one                                          451     487     +36
printLines                                           258     190     -68
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 136/-68)            Total: 68 bytes

1 files changed, 1 insertions, 0 deletions

diff --git a/libbb/Kbuild b/libbb/Kbuild
index 6791299f2..c4aac95bb 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -65,6 +65,7 @@ lib-y += perror_msg_and_die.o
 lib-y += perror_nomsg.o
 lib-y += perror_nomsg_and_die.o
 lib-y += pidfile.o
+lib-y += printable.o
 lib-y += process_escape_sequence.o
 lib-y += procps.o
 lib-y += read.o