shells: do not frocibly enable test, echo and kill _applets_,

just build relevant source and use xxx_main functions.
build system: add a special case when we have exactly one applet enabled
(makes "true", "false", "basename" REALLY tiny).
getopt32: do not use stdio.

function                                             old     new   delta
getopt32                                            1385    1412     +27
make_device                                         1187    1200     +13
basename_main                                        120     127      +7
tcpudpsvd_main                                      1922    1926      +4
testcmd                                                5       -      -5
echocmd                                                5       -      -5
fuser_main                                          1243    1231     -12
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 4/1 up/down: 51/-22)             Total: 29 bytes

1 files changed, 2 insertions, 2 deletions

diff --git a/init/Config.in b/init/Config.in
index 25f439003..a1684d45d 100644
--- a/init/Config.in
+++ b/init/Config.in
@@ -98,13 +98,13 @@ config FEATURE_INITRD
 
 config HALT
         bool "poweroff, halt, and reboot"
-        default y
+        default n
         help
           Stop all processes and either halt, reboot, or power off the system.
 
 config MESG
         bool "mesg"
-        default y
+        default n
         help
           Mesg controls access to your terminal by others.  It is typically
           used to allow or disallow other users to write to your terminal