[XEN PATCH v6 11/31] build: fix clean targets when subdir-y is used

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

The make variable $(subdir-y) isn't used yet but will be in a
following patch. Anything in $(subdir-y) doesn't to have a '/' as
suffix as we already now it's a directory.

Rework the rules so that it doesn't matter whether there is a '/' or
not. It also mimic more closely to the way Linux's Kbuild descend in
subdirectories.

FORCE phony target isn't needed anymore running clean, so it can be
removed.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 xen/scripts/Makefile.clean | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/xen/scripts/Makefile.clean b/xen/scripts/Makefile.clean
index 53379e6102cc..027c200c0efc 100644
--- a/xen/scripts/Makefile.clean
+++ b/xen/scripts/Makefile.clean
@@ -12,19 +12,18 @@ include Makefile
 # Figure out what we need to clean from the various variables
 # ==========================================================================
 subdir-all := $(subdir-y) $(subdir-n) $(subdir-) \
-              $(filter %/, $(obj-y) $(obj-n) $(obj-))
+              $(patsubst %/,%, $(filter %/, $(obj-y) $(obj-n) $(obj-)))
 
 DEPS_RM = $(DEPS) $(DEPS_INCLUDE)
 .PHONY: clean
-clean:: $(addprefix _clean_, $(subdir-all))
+clean:: $(subdir-all)
        rm -f *.o .*.o.tmp *~ core $(DEPS_RM)
 
 # Descending
 # ---------------------------------------------------------------------------
 
-_clean_%/: FORCE
-       $(MAKE) $(clean) $*
+PHONY += $(subdir-all)
+$(subdir-all):
+       $(MAKE) $(clean) $@
 
-# Force execution of pattern rules (for which PHONY cannot be directly used).
-.PHONY: FORCE
-FORCE:
+.PHONY: $(PHONY)
-- 
Anthony PERARD