Upgrade pgbouncer to 1.8.1 (#5077)

* upgrade pgbouncer to 1.8.1

* support PAM/HBA auth type

* update submodule pgbouncer commit

* update pgbouncer's commit to support SSL connection

-change pgbouncer server_tls_ciphers default value

.gitmodules

 [submodule "gpAux/extensions/pgbouncer/source"]
 	path = gpAux/extensions/pgbouncer/source
 	url = https://github.com/greenplum-db/pgbouncer.git
-	branch = master
+	branch = pgbouncer_1_8_1
 [submodule "gpAux/extensions/postgis-2.0.3/source"]
 	path = gpAux/extensions/postgis-2.0.3/source
 	url = https://github.com/greenplum-db/postgis.git

gpAux/Makefile

@@ -897,7 +897,7 @@ ifeq "$(shell uname -s)" "Darwin"
 	echo "pgbouncer can't build on Mac"
 else
 	@if [ ! -f extensions/pgbouncer/source/configure ]; then cd extensions/pgbouncer/source && ./autogen.sh ;fi
-	@cd extensions/pgbouncer/source && ./configure --with-libevent=$(BLD_TOP)/ext/$(BLD_ARCH) --prefix=$(INSTLOC) --enable-evdns
+	@cd extensions/pgbouncer/source && ./configure --with-libevent=$(BLD_TOP)/ext/$(BLD_ARCH) --prefix=$(INSTLOC) --enable-evdns --with-pam
 	$(MAKE) -C extensions/pgbouncer/source install
 endif
 

source @ d85aca63

-Subproject commit ce8f84097c5ef3c41df91c1a445df4c2a984c464
+Subproject commit d85aca63a4006230c22a62b6040c1cfa9bc780b8