tools: Improve diffability/maintainability

Like with commit ae614fb397c2 ("tools: Improve diffability/maintainability")
we also want tools-core to be easy to maintain. While a smaller target,
it's still usefull and makes things nice and consistent.

To avoid duplicating any tools in the comment, simplify the comment
instead.

Signed-off-by: Olliver Schinagl <[email protected]>

tools/Makefile

@@ -147,8 +147,10 @@ $(foreach tool, $(tools-y), $(if $(wildcard $(curdir)/$(tool)/patches),$(eval $(
 
 $(foreach tool, $(filter-out xz,$(tools-y)), $(eval $(curdir)/$(tool)/compile += $(curdir)/xz/compile))
 
-# make any tool depend on tar, xz and patch to ensure that archives can be unpacked and patched properly
-tools-core := tar xz patch
+# make any tool depend on the following to ensure that archives can be unpacked and patched properly
+tools-core += patch
+tools-core += tar
+tools-core += xz
 
 $(foreach tool, $(tools-y), $(eval $(curdir)/$(tool)/compile += $(patsubst %,$(curdir)/%/compile,$(tools-core))))
 tools-y += $(tools-core)