Install the most appropriate PAM settings file

Installing a file referring to common-auth is of no use if that file
doesn't exit.

Don't use "password" entry, xrdp doesn't ever change user password.

.gitignore

@@ -15,6 +15,7 @@ depcomp
 .deps/
 genkeymap/xrdp-genkeymap
 install-sh
+instfiles/pam.d/xrdp-sesman
 keygen/xrdp-keygen
 *.la
 .libs

instfiles/pam.d/Makefile.am

@@ -1,4 +1,9 @@
-EXTRA_DIST = xrdp-sesman
+EXTRA_DIST = \
+  xrdp-sesman.common \
+  xrdp-sesman.other \
+  xrdp-sesman.password-auth
+
+CLEANFILES = xrdp-sesman
 
 if SESMAN_NOPAM
 PAMFILE =
@@ -18,3 +23,15 @@ pamddir=$(sysconfdir)/pam.d
 
 pamd_DATA = \
   $(PAMFILE)
+
+xrdp-sesman:
+	if test -e /etc/pam.d/password-auth; then \
+	  pamrules=xrdp-sesman.password-auth; \
+	else \
+	  if test -e /etc/pam.d/common-auth; then \
+	    pamrules=xrdp-sesman.common; \
+	  else \
+	    pamrules=xrdp-sesman.other; \
+	  fi; \
+	fi; \
+	$(LN_S) $(srcdir)/$$pamrules $@

instfiles/pam.d/xrdp-sesman.common

@@ -2,4 +2,3 @@
 @include common-auth
 @include common-account
 @include common-session
-@include common-password

instfiles/pam.d/xrdp-sesman.password-auth

@@ -0,0 +1,4 @@
+#%PAM-1.0
+auth       include      password-auth
+account    include      password-auth
+session    include      password-auth