[caribou] Don't rebuild docs on every "make" run.

[Daiki Ueno <dueno src gnome org>]

commit c85570782c49531a63ecdd37deb3bcd915b6e573
Author: Daiki Ueno <ueno unixuser org>
Date:   Sun Feb 17 10:57:42 2013 +0900

    Don't rebuild docs on every "make" run.
    
    Create timestamp files to avoid redundant valadoc invocation.
    This is a port of folks bug#691923.

 docs/Makefile.am |   18 ++++++++++++------
 1 files changed, 12 insertions(+), 6 deletions(-)
---
diff --git a/docs/Makefile.am b/docs/Makefile.am
index ef2c61e..5dc9de2 100644
--- a/docs/Makefile.am
+++ b/docs/Makefile.am
@@ -3,7 +3,7 @@ distclean_dirs = \
        gtk-doc \
        $(NULL)
 
-phony_deps = \
+docs = \
        caribou-doc \
        caribou-gtk-doc \
        $(NULL)
@@ -36,8 +36,8 @@ caribougtkdoc_DATA = gtk-doc/caribou/html/*
 caribouimg_DATA = \
        $(NULL)
 
-$(cariboudoc_DATA) $(caribouimg_DATA): caribou-doc
-$(caribougtkdoc_DATA): caribou-gtk-doc
+$(cariboudoc_DATA) $(caribouimg_DATA): caribou-doc.stamp
+$(caribougtkdoc_DATA): caribou-gtk-doc.stamp
 
 valadoc_flags = \
        --force \
@@ -76,22 +76,28 @@ valadoc_flags_caribou = \
        $(caribou_doc_files) \
        $(NULL)
 
-caribou-doc: $(caribou_doc_files)
+caribou-doc.stamp: $(caribou_doc_files)
        $(AM_V_GEN)$(VALADOC) \
                -o caribou/ \
                --doclet=devhelp \
                $(valadoc_flags_caribou) \
                $(NULL)
+       @touch $@
 
-caribou-gtk-doc: $(caribou_doc_files)
+caribou-gtk-doc.stamp: $(caribou_doc_files)
        $(AM_V_GEN)$(VALADOC) \
                -X -l -X $(top_builddir)/libcaribou/.libs/libcaribou.so \
                -o gtk-doc/caribou \
                --doclet=gtkdoc \
                $(valadoc_flags_caribou) \
                $(NULL)
+       @touch $@
 
-.PHONY: $(phony_deps)
+stamps = $(addsuffix .stamp, $(docs))
+
+all: $(stamps)
+
+CLEANFILES = $(stamps)
 
 distclean-local: distclean-docs
 distclean-docs: