build: simplify commands for clean target

Signed-off-by: Mans Rullgard <mans@mansr.com>

subdir.mak

@@ -50,12 +50,12 @@ endif
 
 clean::
 	$(RM) $(addprefix $(SUBDIR),*-example$(EXESUF) *-test$(EXESUF) $(CLEANFILES) $(CLEANSUFFIXES) $(LIBSUFFIXES)) \
-	    $(addprefix $(SUBDIR), $(foreach suffix,$(CLEANSUFFIXES),$(addsuffix /$(suffix),$(DIRS)))) \
+	    $(foreach dir,$(DIRS),$(CLEANSUFFIXES:%=$(SUBDIR)$(dir)/%)) \
 	    $(HOSTOBJS) $(HOSTPROGS)
 
 distclean:: clean
-	$(RM)  $(addprefix $(SUBDIR),$(DISTCLEANSUFFIXES)) \
-            $(addprefix $(SUBDIR), $(foreach suffix,$(DISTCLEANSUFFIXES),$(addsuffix /$(suffix),$(DIRS))))
+	$(RM) $(DISTCLEANSUFFIXES:%=$(SUBDIR)%) \
+	    $(foreach dir,$(DIRS),$(DISTCLEANSUFFIXES:%=$(SUBDIR)$(dir)/%))
 
 install-lib$(NAME)-shared: $(SUBDIR)$(SLIBNAME)
 	$(Q)mkdir -p "$(SHLIBDIR)"