cleanup dependency dups

Several targets were used in a duplicated way
that made no harm but no sense either.

features.in/build-distro/config.mk

@@ -1,2 +1,3 @@
-use/build-distro: boot/isolinux
+# hooked from ../../lib/sugar.mk
+use/build-distro:
 	@$(call add_feature)

features.in/build-ve/config.mk

@@ -1,2 +1,3 @@
+# hooked from ../../lib/sugar.mk
 use/build-ve:
 	@$(call add_feature)

lib/distro.mk

@@ -11,7 +11,7 @@ sub/%:
 	@$(call add,SUBPROFILES,$(@:sub/%=%))
 
 # install media bootloader
-boot/%: profile/bare use/syslinux
+boot/%: use/syslinux
 	@$(call set,BOOTLOADER,$*)
 
 # fundamental targets
@@ -25,8 +25,8 @@ distro/.base: distro/.init
 
 # bootloader test target
 distro/syslinux: distro/.init \
-	use/syslinux use/syslinux/localboot.cfg \
-	use/syslinux/ui-vesamenu use/hdt use/memtest
+	use/syslinux/localboot.cfg use/syslinux/ui-vesamenu \
+	use/hdt use/memtest
 
 # something marginally useful (as a network-only installer)
 # NB: doesn't carry stage3 thus cannot use/bootloader