dos2unix: tiny shrink
login,su: fix setup_environment() so that it works as intended
          (parameter names were a bit misleading)
fdisk: shrink
help text: shrink

function                                             old     new   delta
login_main                                          1658    1701     +43
setup_environment                                    206     203      -3
dos_compatible_flag                                    4       1      -3
dos2unix_main                                        383     375      -8
get_boot                                            1724    1702     -22
fdisk_main                                          2949    2889     -60
packed_usage                                       24250   23948    -302
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/6 up/down: 43/-398)          Total: -355 bytes
   text    data     bss     dec     hex filename
 798768     661    7428  806857   c4fc9 busybox_old
 798327     658    7428  806413   c4e0d busybox_unstripped

diff --git a/include/libbb.h b/include/libbb.h
index 73638a1..09deba6 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -941,20 +941,20 @@
 extern int restricted_shell(const char *shell);
 
 /* setup_environment:
- * if loginshell = 1: cd(pw->pw_dir), clear environment, then set
+ * if clear_env = 1: cd(pw->pw_dir), clear environment, then set
  *   TERM=(old value)
  *   USER=pw->pw_name, LOGNAME=pw->pw_name
  *   PATH=bb_default_[root_]path
  *   HOME=pw->pw_dir
  *   SHELL=shell
- * else if changeenv = 1:
+ * else if change_env = 1:
  *   if not root (if pw->pw_uid != 0):
  *     USER=pw->pw_name, LOGNAME=pw->pw_name
  *   HOME=pw->pw_dir
  *   SHELL=shell
  * else does nothing
  */
-extern void setup_environment(const char *shell, int loginshell, int changeenv, const struct passwd *pw);
+extern void setup_environment(const char *shell, int clear_env, int change_env, const struct passwd *pw);
 extern int correct_password(const struct passwd *pw);
 /* Returns a ptr to static storage */
 extern char *pw_encrypt(const char *clear, const char *salt);