common.mk: directory timestamps

* common.mk, enc/Makefile.in: moved timestamp files for
  directories under the specific directory, to get rid of match
  with files under the source directory.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55693 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

common.mk

@@ -35,11 +35,12 @@ DOCLIE_GIT_REF = v1.1.5
 
 STATIC_RUBY   = static-ruby
 
+TIMESTAMPDIR  = $(EXTOUT)/.timestamp
 EXTCONF       = extconf.rb
 LIBRUBY_EXTS  = ./.libruby-with-ext.time
 REVISION_H    = ./.revision.time
-PLATFORM_D    = ./$(PLATFORM_DIR)/.time
-ENC_TRANS_D   = ./enc/trans/.time
+PLATFORM_D    = $(TIMESTAMPDIR)/.$(PLATFORM_DIR).time
+ENC_TRANS_D   = $(TIMESTAMPDIR)/.enc-trans.time
 RDOCOUT       = $(EXTOUT)/rdoc
 HTMLOUT       = $(EXTOUT)/html
 CAPIOUT       = doc/capi

enc/Makefile.in

@@ -20,8 +20,9 @@ TRANSSODIR = $(ENCSODIR)/trans
 DLEXT = @DLEXT@
 OBJEXT = @OBJEXT@
 LIBEXT = @LIBEXT@
-ENC_TRANS_D   = ./enc/trans/.time
-ENC_TRANS_SO_D = ./enc/trans/.so.time
+TIMESTAMPDIR  = $(EXTOUT)/.timestamp
+ENC_TRANS_D   = $(TIMESTAMPDIR)/.enc-trans.time
+ENC_TRANS_SO_D = $(TIMESTAMPDIR)/.enc-trans.so.time
 
 BUILTIN_ENCS	= enc/ascii.c enc/us_ascii.c\
 		  enc/unicode.c enc/utf_8.c