btrfs-progs: add separate make target to clean docs

Regenerating the asciidoc takes much longer now and makes quick build
tests long. There's separate clean-doc target for that and clean-all
that cleans docs and sources.

Signed-off-by: David Sterba <dsterba@suse.cz>

Makefile

@@ -55,9 +55,9 @@ btrfs_convert_libs = -lext2fs -lcom_err
 btrfs_image_libs = -lpthread
 btrfs_fragment_libs = -lgd -lpng -ljpeg -lfreetype
 
-SUBDIRS = Documentation
-BUILDDIRS = $(patsubst %,build-%,$(SUBDIRS))
-INSTALLDIRS = $(patsubst %,install-%,$(SUBDIRS))
+SUBDIRS =
+BUILDDIRS = $(patsubst %,build-%,$(SUBDIRS)) build-Documentation
+INSTALLDIRS = $(patsubst %,install-%,$(SUBDIRS)) install-Documentation
 CLEANDIRS = $(patsubst %,clean-%,$(SUBDIRS))
 
 .PHONY: $(SUBDIRS)
@@ -119,7 +119,7 @@ endif
 	@echo "    [CC]     $@"
 	$(Q)$(CC) $(AM_CFLAGS) $(STATIC_CFLAGS) -c $< -o $@
 
-all: $(progs) manpages $(BUILDDIRS)
+all: $(progs) $(BUILDDIRS)
 $(SUBDIRS): $(BUILDDIRS)
 $(BUILDDIRS):
 	@echo "Making all in $(patsubst build-%,%,$@)"
@@ -222,6 +222,8 @@ send-test: $(objects) $(libs) send-test.o
 manpages:
 	$(Q)$(MAKE) $(MAKEOPTS) -C Documentation
 
+clean-all: clean-doc clean
+
 clean: $(CLEANDIRS)
 	@echo "Cleaning"
 	$(Q)rm -f $(progs) cscope.out *.o *.o.d btrfs-convert btrfs-image btrfs-select-super \
@@ -230,6 +232,10 @@ clean: $(CLEANDIRS)
 	      version.h $(check_defs) \
 	      $(libs) $(lib_links)
 
+clean-doc:
+	@echo "Cleaning Documentation"
+	$(Q)$(MAKE) $(MAKEOPTS) -C Documentation clean
+
 $(CLEANDIRS):
 	@echo "Cleaning $(patsubst clean-%,%,$@)"
 	$(Q)$(MAKE) $(MAKEOPTS) -C $(patsubst clean-%,%,$@) clean