Fix link failures due to snprintf/strerror changes.

snprintf.c requires isnan(), which requires -lm on some platforms.
libpq never bothered with -lm before, but now it needs it.

strerror.c tries to translate a string or two, which requires -lintl.
We'd managed never to need that anywhere in ecpg/pgtypeslib/ before,
but now we do.

Per buildfarm and a report from Peter Eisentraut.

Discussion: https://postgr.es/m/20180926190934.ea4xvzhkayuw7gkx@alap3.anarazel.de
Discussion: https://postgr.es/m/f67b5008-9f01-057f-2bff-558cb53af851@2ndquadrant.com

src/interfaces/ecpg/pgtypeslib/Makefile

@@ -25,7 +25,7 @@ override CFLAGS += $(PTHREAD_CFLAGS)
 # Need to recompile any libpgport object files
 LIBS := $(filter-out -lpgport, $(LIBS))
 
-SHLIB_LINK += $(filter -lm, $(LIBS))
+SHLIB_LINK += $(filter -lintl -lm, $(LIBS))
 
 SHLIB_EXPORTS = exports.txt
 

src/interfaces/libpq/Makefile

@@ -78,9 +78,9 @@ endif
 # shared library link.  (The order in which you list them here doesn't
 # matter.)
 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)
+SHLIB_LINK += $(filter -lcrypt -ldes -lcom_err -lcrypto -lk5crypto -lkrb5 -lgssapi_krb5 -lgss -lgssapi -lssl -lsocket -lnsl -lresolv -lintl -lm, $(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 -lk5crypto -lkrb5 -lgssapi32 -lssl -lsocket -lnsl -lresolv -lintl -lm $(PTHREAD_LIBS), $(LIBS)) $(LDAP_LIBS_FE)
 endif
 ifeq ($(PORTNAME), win32)
 SHLIB_LINK += -lshell32 -lws2_32 -lsecur32 $(filter -leay32 -lssleay32 -lcomerr32 -lkrb5_32, $(LIBS))