Move gitk to its own subdirectory

This is to prepare for gitk i18n effort that makes gitk not a single file
project anymore.  We may use subproject to bind git.git and gitk.git more
loosely in the future, but we do not want to require everybody to have
subproject aware git to be able to pull from git.git yet.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -270,9 +270,6 @@ ALL_PROGRAMS += git-merge-subtree$X
 
 # what 'all' will build but not install in gitexecdir
 OTHER_PROGRAMS = git$X gitweb/gitweb.cgi
-ifndef NO_TCLTK
-OTHER_PROGRAMS += gitk-wish
-endif
 
 # Set paths to tools early so that they can be used for version tests.
 ifndef SHELL_PATH
@@ -772,6 +769,7 @@ endif
 all::
 ifndef NO_TCLTK
 	$(QUIET_SUBDIR0)git-gui $(QUIET_SUBDIR1) all
+	$(QUIET_SUBDIR0)gitk-git $(QUIET_SUBDIR1) all
 endif
 	$(QUIET_SUBDIR0)perl $(QUIET_SUBDIR1) PERL_PATH='$(PERL_PATH_SQ)' prefix='$(prefix_SQ)' all
 	$(QUIET_SUBDIR0)templates $(QUIET_SUBDIR1)
@@ -779,12 +777,6 @@ endif
 strip: $(PROGRAMS) git$X
 	$(STRIP) $(STRIP_OPTS) $(PROGRAMS) git$X
 
-gitk-wish: gitk GIT-GUI-VARS
-	$(QUIET_GEN)$(RM) $@ $@+ && \
-	sed -e '1,3s|^exec .* "$$0"|exec $(subst |,'\|',$(TCLTK_PATH_SQ)) "$$0"|' <gitk >$@+ && \
-	chmod +x $@+ && \
-	mv -f $@+ $@
-
 git.o: git.c common-cmds.h GIT-CFLAGS
 	$(QUIET_CC)$(CC) -DGIT_VERSION='"$(GIT_VERSION)"' \
 		$(ALL_CFLAGS) -c $(filter %.c,$^)
@@ -1025,7 +1017,7 @@ install: all
 	$(MAKE) -C templates DESTDIR='$(DESTDIR_SQ)' install
 	$(MAKE) -C perl prefix='$(prefix_SQ)' install
 ifndef NO_TCLTK
-	$(INSTALL) gitk-wish '$(DESTDIR_SQ)$(bindir_SQ)'/gitk
+	$(MAKE) -C gitk-git install
 	$(MAKE) -C git-gui install
 endif
 	if test 'z$(bindir_SQ)' != 'z$(gitexecdir_SQ)'; \
@@ -1118,7 +1110,7 @@ clean:
 	$(MAKE) -C templates/ clean
 	$(MAKE) -C t/ clean
 ifndef NO_TCLTK
-	$(RM) gitk-wish
+	$(MAKE) -C gitk-git clean
 	$(MAKE) -C git-gui clean
 endif
 	$(RM) GIT-VERSION-FILE GIT-CFLAGS GIT-GUI-VARS

gitk-git/Makefile

@@ -0,0 +1,29 @@
+# The default target of this Makefile is...
+all::
+
+prefix ?= $(HOME)
+bindir ?= $(prefix)/bin
+TCLTK_PATH ?= wish
+INSTALL ?= install
+RM ?= rm -f
+
+DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
+bindir_SQ = $(subst ','\'',$(bindir))
+TCLTK_PATH_SQ = $(subst ','\'',$(TCLTK_PATH))
+
+ifndef V
+	QUIET          = @
+	QUIET_GEN      = $(QUIET)echo '   ' GEN $@ &&
+endif
+
+all:: gitk-wish
+install:: all
+	$(INSTALL) gitk-wish '$(DESTDIR_SQ)$(bindir_SQ)'/gitk
+clean::
+	$(RM) gitk-wish
+
+gitk-wish: gitk
+	$(QUIET_GEN)$(RM) $@ $@+ && \
+	sed -e '1,3s|^exec .* "$$0"|exec $(subst |,'\|',$(TCLTK_PATH_SQ)) "$$0"|' <gitk >$@+ && \
+	chmod +x $@+ && \
+	mv -f $@+ $@