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, 0 insertions, 27 deletions

diff --git a/libbb/error_msg_and_die.c b/libbb/error_msg_and_die.c
index 0e99a03..addd818 100644
--- a/libbb/error_msg_and_die.c
+++ b/libbb/error_msg_and_die.c
@@ -9,33 +9,6 @@
 
 #include "libbb.h"
 
-int die_sleep;
-#if ENABLE_FEATURE_PREFER_APPLETS || ENABLE_HUSH
-jmp_buf die_jmp;
-#endif
-
-void xfunc_die(void)
-{
-	if (die_sleep) {
-		if ((ENABLE_FEATURE_PREFER_APPLETS || ENABLE_HUSH)
-		 && die_sleep < 0
-		) {
-			/* Special case. We arrive here if NOFORK applet
-			 * calls xfunc, which then decides to die.
-			 * We don't die, but jump instead back to caller.
-			 * NOFORK applets still cannot carelessly call xfuncs:
-			 * p = xmalloc(10);
-			 * q = xmalloc(10); // BUG! if this dies, we leak p!
-			 */
-			/* -2222 means "zero" (longjmp can't pass 0)
-			 * run_nofork_applet() catches -2222. */
-			longjmp(die_jmp, xfunc_error_retval ? xfunc_error_retval : -2222);
-		}
-		sleep(die_sleep);
-	}
-	exit(xfunc_error_retval);
-}
-
 void bb_error_msg_and_die(const char *s, ...)
 {
 	va_list p;