Add missing dependency of pg_dumpall to WIN32RES.

When cross-building to windows, or building with mingw on windows, the build
could fail with
  x86_64-w64-mingw32-gcc: error: win32ver.o: No such file or director
because pg_dumpall didn't depend on WIN32RES, but it's recipe references
it. The build nevertheless succeeded most of the time, due to
pg_dump/pg_restore having the required dependency, causing win32ver.o to be
built.

Reported-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/CA+hUKGJeekpUPWW6yCVdf9=oBAcCp86RrBivo4Y4cwazAzGPng@mail.gmail.com
Backpatch: 10-, omission present on all live branches

Author: anarazel

src/bin/pg_dump/Makefile

@@ -40,7 +40,7 @@ pg_dump: pg_dump.o common.o pg_dump_sort.o $(OBJS) | submake-libpq submake-libpg
 pg_restore: pg_restore.o $(OBJS) | submake-libpq submake-libpgport submake-libpgfeutils
 	$(CC) $(CFLAGS) pg_restore.o $(OBJS) $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)
 
-pg_dumpall: pg_dumpall.o dumputils.o | submake-libpq submake-libpgport submake-libpgfeutils
+pg_dumpall: pg_dumpall.o dumputils.o $(WIN32RES) | submake-libpq submake-libpgport submake-libpgfeutils
 	$(CC) $(CFLAGS) pg_dumpall.o dumputils.o $(WIN32RES) $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)
 
 install: all installdirs