unix Makefile.src and hints

Change the handling for windowing system specific files so that
when building for more than one set, each gets compiled as a set
instead of some being interspersed among rival window systems.
Put differently, handle tile.o specially so that there's no need
for the hints to sort the WINOBJ list in order to avoid tile.o
duplication.

So the order of compilation is
  common source files
  unix-specific files
  tty files
  curses files
  X11 files
  Qt files
  tile.c (if applicable), version.c, date.c

Previously, some of the X11 files were scattered around among the
others because of the spelling of their file names.

Only matters if you're watching the progress of a build.

sys/unix/hints/include/multiw-2.370

@@ -78,6 +78,8 @@ endif
 WINCFLAGS=
 WINSRC =
 WINOBJ0 =
+XTRASRC =
+XTRAOBJ =
 
 ifdef WANT_WIN_TTY
 WINSRC += $(WINTTYSRC)
@@ -96,12 +98,16 @@ ifdef WANT_WIN_X11
 WINCFLAGS += -DX11_GRAPHICS
 WINSRC += $(WIINX11SRC)
 WINOBJ0 += $(WINX11OBJ)
+XTRASRC += tile.c
+XTRAOBJ += $(TARGETPFX)tile.o
 endif
 
 ifdef WANT_WIN_QT
 WINCFLAGS += -DQT_GRAPHICS
 WINSRC += $(WINQTSRC)
 WINOBJ0 += $(WINQTOBJ)
+XTRASRC += tile.c
+XTRAOBJ += $(TARGETPFX)tile.o
 endif
 
 #end of hints/include/multiw-2.370