[Patch] Add missing libraries to Libs.private of libpq.pc

Hello

The following patch, which we added to build mingw-postgresql on Fedora,
adds some missing libraries to Libs.private of libpq.pc, discovered when
attempting to statically link with libpq:

-lz: is required by -lcrypto
-liconv: is required by -lintl (though possibly depends on whether
gettext was compiled with iconv support)

Thanks
Sandro

diff -rupN postgresql-11.5/src/interfaces/libpq/Makefile
postgresql-11.5-new/src/interfaces/libpq/Makefile
--- postgresql-11.5/src/interfaces/libpq/Makefile    2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/libpq/Makefile 2020-04-07
13:49:00.801203610 +0200
@@ -80,10 +80,10 @@ endif
 ifneq ($(PORTNAME), win32)
 SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lk5crypto
-lkrb5 -lgssapi_krb5 -lgss -lgssapi -lssl -lsocket -lnsl -lresolv
-lintl, $(LIBS)) $(LDAP_LIBS_FE) $(PTHREAD_LIBS)
 else
-SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lk5crypto
-lkrb5 -lgssapi32 -lssl -lsocket -lnsl -lresolv -lintl $(PTHREAD_LIBS),
$(LIBS)) $(LDAP_LIBS_FE)
+SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lz -lk5crypto
-lkrb5 -lgssapi32 -lssl -lsocket -lnsl -lresolv -lintl $(PTHREAD_LIBS),
$(LIBS)) $(LDAP_LIBS_FE)
 endif
 ifeq ($(PORTNAME), win32)
-SHLIB_LINK += -lshell32 -lws2_32 -lsecur32 $(filter -leay32 -lssleay32
-lcomerr32 -lkrb5_32, $(LIBS))
+SHLIB_LINK += -lshell32 -lws2_32 -lsecur32 -liconv $(filter -leay32
-lssleay32 -lcomerr32 -lkrb5_32, $(LIBS))
 endif

 SHLIB_EXPORTS = exports.txt