Merge bitcoin#15446: Improve depends debuggability

6d44c5e depends: Add commands for each package for each stage (Carl Dong)
80f0e05 depends: Preprocessing doesn't care about deps (Carl Dong)

Pull request description:

  Adds make targets for each package for each stage, e.g.

  ```sh
  make zeromq_configured
  ```

ACKs for commit 6d44c5:
  MarcoFalke:
    ACK 6d44c5e (Haven't looked at the code changes, but adding this feature makes sense)
  ryanofsky:
    ACK 6d44c5e

Tree-SHA512: f1ac0aecfd2372aed09ca63603e2634552cb3f6ff9d610f958e2a66952d7d9e870b4c32b7d996886879e6d3016532272e8b1a10c13ed7b31009c6c96f786db9f

Author: MarcoFalke

depends/Makefile

@@ -192,4 +192,6 @@ download-win:
 	@$(MAKE) -s HOST=x86_64-w64-mingw32 download-one
 download: download-osx download-linux download-win
 
+$(foreach package,$(all_packages),$(eval $(call ext_add_stages,$(package))))
+
 .PHONY: install cached clean clean-all download-one download-osx download-linux download-win download check-packages check-sources

depends/funcs.mk

@@ -171,13 +171,13 @@ $($(1)_extracted): | $($(1)_fetched)
 	$(AT)mkdir -p $$(@D)
 	$(AT)cd $$(@D); $(call $(1)_extract_cmds,$(1))
 	$(AT)touch $$@
-$($(1)_preprocessed): | $($(1)_dependencies) $($(1)_extracted)
+$($(1)_preprocessed): | $($(1)_extracted)
 	$(AT)echo Preprocessing $(1)...
 	$(AT)mkdir -p $$(@D) $($(1)_patch_dir)
 	$(AT)$(foreach patch,$($(1)_patches),cd $(PATCHES_PATH)/$(1); cp $(patch) $($(1)_patch_dir) ;)
 	$(AT)cd $$(@D); $(call $(1)_preprocess_cmds, $(1))
 	$(AT)touch $$@
-$($(1)_configured): | $($(1)_preprocessed)
+$($(1)_configured): | $($(1)_dependencies) $($(1)_preprocessed)
 	$(AT)echo Configuring $(1)...
 	$(AT)rm -rf $(host_prefix); mkdir -p $(host_prefix)/lib; cd $(host_prefix); $(foreach package,$($(1)_all_dependencies), tar --no-same-owner -xf $($(package)_cached); )
 	$(AT)mkdir -p $$(@D)
@@ -214,6 +214,14 @@ $(1): | $($(1)_cached_checksum)
 
 endef
 
+stages = fetched extracted preprocessed configured built staged postprocessed cached cached_checksum
+
+define ext_add_stages
+$(foreach stage,$(stages),
+          $(1)_$(stage): $($(1)_$(stage))
+          .PHONY: $(1)_$(stage))
+endef
+
 # These functions create the build targets for each package. They must be
 # broken down into small steps so that each part is done for all packages
 # before moving on to the next step. Otherwise, a package's info