* configure.in: Added option --enable-account-tools-setuid to

enable/disable the usage of PAM to authenticate the callers of
	account management tools: chage, chgpasswd, chpasswd, groupadd,
	groupdel, groupmod, useradd, userdel, usermod.
	* src/Makefile.am: Do not link the above tools with libpam if
	account-tools-setuid is disabled.
	* src/userdel.c, src/newusers.c, src/chpasswd.c, src/usermod.c,
	src/groupdel.c, src/chgpasswd.c, src/useradd.c, src/groupmod.c,
	src/groupadd.c, src/chage.c: Implement ACCT_TOOLS_SETUID
	(--enable-account-tools-setuid).
	* etc/pam.d/Makefile.am: Install the pam service file for the
	above tools only when needed.
	* src/useradd.c, src/userdel.c, src/usermod.c: It is no more
	needed to initialize retval to PAM_SUCCESS.

etc/pam.d/Makefile.am

@@ -2,22 +2,26 @@
 # and also cooperate to make a distribution for `make dist'
 
 pamd_files = \
-	chage \
 	chfn \
+	chsh \
+	groupmems \
+	login \
+	passwd \
+	su
+
+if ACCT_TOOLS_SETUID
+pamd_files += \
+	chage \
 	chgpasswd \
 	chpasswd \
-	chsh \
 	groupadd \
 	groupdel \
-	groupmems \
 	groupmod \
-	login \
 	newusers \
-	passwd \
-	su \
 	useradd \
 	userdel \
 	usermod
+endif
 
 if USE_PAM
 pamddir = $(sysconfdir)/pam.d