Add BSD authentication method.

Create a "bsd" auth method that works the same as "password" so far as
clients are concerned, but calls the BSD Authentication service to
check the password.  This is currently only available on OpenBSD.

Marisa Emerson, reviewed by Thomas Munro

configure

@@ -827,6 +827,7 @@ with_python
 with_gssapi
 with_krb_srvnam
 with_pam
+with_bsd_auth
 with_ldap
 with_bonjour
 with_openssl
@@ -1516,6 +1517,7 @@ Optional Packages:
   --with-krb-srvnam=NAME  default service principal name in Kerberos (GSSAPI)
                           [postgres]
   --with-pam              build with PAM support
+  --with-bsd-auth         build with BSD Authentication support
   --with-ldap             build with LDAP support
   --with-bonjour          build with Bonjour support
   --with-openssl          build with OpenSSL support
@@ -5570,6 +5572,41 @@ fi
 $as_echo "$with_pam" >&6; }
 
 
+#
+# BSD AUTH
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with BSD Authentication support" >&5
+$as_echo_n "checking whether to build with BSD Authentication support... " >&6; }
+
+
+
+# Check whether --with-bsd-auth was given.
+if test "${with_bsd_auth+set}" = set; then :
+  withval=$with_bsd_auth;
+  case $withval in
+    yes)
+
+$as_echo "#define USE_BSD_AUTH 1" >>confdefs.h
+
+      ;;
+    no)
+      :
+      ;;
+    *)
+      as_fn_error $? "no argument expected for --with-bsd-auth option" "$LINENO" 5
+      ;;
+  esac
+
+else
+  with_bsd_auth=no
+
+fi
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_bsd_auth" >&5
+$as_echo "$with_bsd_auth" >&6; }
+
+
 #
 # LDAP
 #
@@ -10522,6 +10559,17 @@ fi
 
 done
 
+fi
+
+if test "$with_bsd_auth" = yes ; then
+  ac_fn_c_check_header_mongrel "$LINENO" "bsd_auth.h" "ac_cv_header_bsd_auth_h" "$ac_includes_default"
+if test "x$ac_cv_header_bsd_auth_h" = xyes; then :
+
+else
+  as_fn_error $? "header file <bsd_auth.h> is required for BSD Authentication support" "$LINENO" 5
+fi
+
+
 fi
 
 if test "$with_systemd" = yes ; then