btrfs-progs: make pretty Documentation/ build match the rest

This is the most important patch ever. ;)

I found this to be less aesthetically pleasing than it was before:

[CC] btrfstune.o
Making all in Documentation
ASCIIDOC btrfs-convert.xml
[LD] btrfstune
XMLTO btrfs-convert.8
[CC] btrfs-show-super.o
GZIP btrfs-convert.8.gz
[LD] btrfs-show-super
ASCIIDOC btrfs-debug-tree.xml
XMLTO btrfs-debug-tree.8

so I shortened the pretty-text to match what we had before.

Also, make clean "quiet" like it is in the top dir.

---

If folks don't like the 2-letter abbreviations, obviously the patch just isn't that important.

index 45299bb..03a5cd5 100644
@@ -54,9 +54,10 @@ BTRFS_VERSION = $(shell sed -n 's/.*BTRFS_BUILD_VERSION "Btrfs \(.*\)"/\1/p'\
 
 ifneq ($(findstring $(MAKEFLAGS),s),s)
 ifndef V
-	QUIET_ASCIIDOC	= @echo '   ' ASCIIDOC $@;
-	QUIET_XMLTO	= @echo '   ' XMLTO $@;
-	QUIET_GZIP	= @echo '   ' GZIP $@;
+	QUIET_RM	= @
+	QUIET_ASCIIDOC	= @echo "    [AD]     $@";
+	QUIET_XMLTO	= @echo "    [XT]     $@";
+	QUIET_GZIP	= @echo "    [GZ]     $@";
 	QUIET_STDERR	= 2> /dev/null
 	QUIET_SUBDIR0	= +@subdir=
 	QUIET_SUBDIR1	= ;$(NO_SUBDIR) echo '   ' SUBDIR $$subdir; \

@@ -77,7 +78,7 @@ install-man: man
 	$(LNS) btrfs-check.8.gz $(DESTDIR)$(man8dir)
 
 clean:
-	$(RM) *.xml *.xml+ *.8 *.8.gz
+	$(QUIET_RM)$(RM) *.xml *.xml+ *.8 *.8.gz
 
 %.8.gz : %.8
 	$(QUIET_GZIP)$(GZIP) -n -c $< > $@

Oh it is :)

I like the prettyfied output, but XT or AD look unfamiliar in this context. I've tried a few tweaks, is this change ok for you?

    [LD]     btrfs-show-super
    [ASCII]  btrfs-property.xml
    [XMLTO]  btrfs-debug-tree.8
    [XMLTO]  btrfstune.8
    [LD]     btrfs-image

Full ASCIIDOC would need to update all the two-letter strings, does not seem justified.