special-case {true,false,test} --help

This also removes their help texts.

function                                             old     new   delta
run_applet_no_and_exit                               442     452     +10
packed_usage                                       30713   30625     -88

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

coreutils/true.c

@@ -10,11 +10,9 @@
 /* BB_AUDIT SUSv3 compliant */
 /* http://www.opengroup.org/onlinepubs/007904975/utilities/true.html */
 
-//usage:#define true_trivial_usage
-//usage:       ""
-//usage:#define true_full_usage "\n\n"
-//usage:       "Return an exit code of TRUE (0)"
-//usage:
+/* "true --help" is special-cased to ignore --help */
+//usage:#define true_trivial_usage NOUSAGE_STR
+//usage:#define true_full_usage ""
 //usage:#define true_example_usage
 //usage:       "$ true\n"
 //usage:       "$ echo $?\n"