hush: fix NOMMU hangs in pseudo_exec_argv. Add forgotted setting

 of signal mask. Reuse same help string in all shells.

function                                             old     new   delta
builtin_exit                                          49      47      -2
pseudo_exec_argv                                     149     145      -4
builtin_help                                          74      63     -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-17)             Total: -17 bytes
   text    data     bss     dec     hex filename
 825379     476    7616  833471   cb7bf busybox_old
 825341     476    7616  833433   cb799 busybox_unstripped

1 files changed, 3 insertions, 2 deletions

diff --git a/shell/lash_unused.c b/shell/lash_unused.c
index 90b1f56cf..21ea5471b 100644
--- a/shell/lash_unused.c
+++ b/shell/lash_unused.c
@@ -312,8 +312,9 @@ static int builtin_help(struct child_prog UNUSED_PARAM *dummy)
 {
         const struct built_in_command *x;
 
-        printf("\nBuilt-in commands:\n"
-               "-------------------\n");
+        printf("\n"
+                "Built-in commands:\n"
+                "------------------\n");
         for (x = bltins; x <= &VEC_LAST(bltins); x++) {
                 if (x->descr == NULL)
                         continue;