sendmail: fix wrong vfork usage here too
*: shorten error texts

function                                             old     new   delta
launch_helper                                          -     151    +151
vfork_or_die                                          20       -     -20
sendgetmail_main                                    1946    1848     -98
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 0/1 up/down: 151/-118)           Total: 33 bytes

diff --git a/archival/libunarchive/open_transformer.c b/archival/libunarchive/open_transformer.c
index a6bc623..a5ee971 100644
--- a/archival/libunarchive/open_transformer.c
+++ b/archival/libunarchive/open_transformer.c
@@ -23,11 +23,11 @@
 #if BB_MMU
 	pid = fork();
 	if (pid == -1)
-		bb_perror_msg_and_die("can't fork");
+		bb_perror_msg_and_die("vfork" + 1);
 #else
 	pid = vfork();
 	if (pid == -1)
-		bb_perror_msg_and_die("can't vfork");
+		bb_perror_msg_and_die("vfork");
 #endif
 
 	if (pid == 0) {