libbb: switch bb_ask_noecho() to "mallocing" string return API

function                                             old     new   delta
bb_ask_noecho                                        313     330     +17
get_cred_or_die                                      125     115     -10
passwd_main                                          995     958     -37
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/2 up/down: 17/-47)            Total: -30 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/mailutils/mail.c b/mailutils/mail.c
index 0fc615a..7af7edd 100644
--- a/mailutils/mail.c
+++ b/mailutils/mail.c
@@ -163,8 +163,8 @@
 void FAST_FUNC get_cred_or_die(int fd)
 {
 	if (isatty(fd)) {
-		G.user = xstrdup(bb_ask_noecho(fd, /* timeout: */ 0, "User: "));
-		G.pass = xstrdup(bb_ask_noecho(fd, /* timeout: */ 0, "Password: "));
+		G.user = bb_ask_noecho(fd, /* timeout: */ 0, "User: ");
+		G.pass = bb_ask_noecho(fd, /* timeout: */ 0, "Password: ");
 	} else {
 		G.user = xmalloc_reads(fd, /* maxsize: */ NULL);
 		G.pass = xmalloc_reads(fd, /* maxsize: */ NULL);