Fix for coroutine/win32/Context.obj

* coroutine/win32/Context.asm: old ml version 9 needs CPU
  directive before `.model` directive.

* win32/Makefile.sub: specify object directories to separate Win32
  and Win64 targets.  Win32 rule was overridden by Win64 rule and
  just ignored.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66059 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

coroutine/win32/Context.asm

@@ -5,6 +5,7 @@
 ;;  Copyright, 2018, by Samuel Williams. All rights reserved.
 ;;
 
+.386
 .model flat
 
 .code

win32/Makefile.sub

@@ -1225,10 +1225,10 @@ $(ruby_pc): $(RBCONFIG)
 		-output=$@ -mode=$(INSTALL_DATA_MODE) -config=rbconfig.rb \
 		$(srcdir)/template/ruby.pc.in
 
-{$(srcdir)/coroutine/Win32}.asm.obj:
+{$(srcdir)/coroutine/Win32}.asm{coroutine/Win32}.obj:
 	$(ECHO) assembling $(<:\=/)
 	$(Q) $(AS) $(ASFLAGS) $(XCFLAGS) $(CPPFLAGS) $(COUTFLAG)$@ -c $(<:\=/)
-{$(srcdir)/coroutine/Win64}.asm.obj:
+{$(srcdir)/coroutine/Win64}.asm{coroutine/Win64}.obj:
 	$(ECHO) assembling $(<:\=/)
 	$(Q) $(AS) $(ASFLAGS) $(XCFLAGS) $(CPPFLAGS) $(COUTFLAG)$@ -c $(<:\=/)