Assorted cleanups.

Makefile

@@ -8,28 +8,32 @@ srcdir = .
 top_srcdir = .
 
 
+# info: src/stub needs GNU make 3.81 and special build tools
+BUILD_STUB = 0
+ifneq ($(wildcard $(HOME)/local/bin/bin-upx/.),)
+BUILD_STUB = 1
+endif
+ifneq ($(wildcard $(HOME)/bin/bin-upx/.),)
+BUILD_STUB = 1
+endif
+ifneq ($(findstring $(firstword $(MAKE_VERSION)),3.79 3.79.1 3.80),)
+BUILD_STUB = 0
+endif
+
+
 default:
 	@echo "UPX info: please choose a target for 'make'"
 
 all mostlyclean clean distclean maintainer-clean:
-ifneq ($(wildcard $(HOME)/local/bin/bin-upx),)
-	# this needs special build tools
+ifeq ($(BUILD_STUB),1)
 	$(MAKE) -C src/stub $@
-else
-ifneq ($(wildcard $(HOME)/bin/bin-upx),)
-	# this needs special build tools
-	$(MAKE) -C src/stub $@
-endif
 endif
 	$(MAKE) -C src $@
 	$(MAKE) -C doc $@
 
-dist: distclean
-	false
-
 # automatically generate ChangeLog from Mercurial repo
 ChangeLog:
-ifneq ($(wildcard .hg/data),)
+ifneq ($(wildcard .hg/data/.),)
 	hg log --style=changelog > $@
 else
 	@echo "UPX info: no hg repo found"
@@ -37,5 +41,5 @@ endif
 
 
 .PHONY: default all mostlyclean clean distclean maintainer-clean
-.PHONY: dist ChangeLog
+.PHONY: ChangeLog