Build libpgfeutils before pg_isready.

Every program having -lpgfeutils in LDFLAGS must have this dependency,
whether or not the program uses a libpgfeutils symbol.  Back-patch to
9.6, where libpgfeutils was introduced.

src/bin/scripts/Makefile

@@ -35,7 +35,7 @@ dropuser: dropuser.o common.o | submake-libpq submake-libpgport submake-libpgfeu
 clusterdb: clusterdb.o common.o | submake-libpq submake-libpgport submake-libpgfeutils
 vacuumdb: vacuumdb.o common.o | submake-libpq submake-libpgport submake-libpgfeutils
 reindexdb: reindexdb.o common.o | submake-libpq submake-libpgport submake-libpgfeutils
-pg_isready: pg_isready.o common.o | submake-libpq submake-libpgport
+pg_isready: pg_isready.o common.o | submake-libpq submake-libpgport submake-libpgfeutils
 
 install: all installdirs
 	$(INSTALL_PROGRAM) createdb$(X)   '$(DESTDIR)$(bindir)'/createdb$(X)