build: Make Windows-specific targets available for Windows builds only

Makefile.am

@@ -78,6 +78,7 @@ COVERAGE_INFO = $(COV_TOOL_WRAPPER) baseline.info \
 dist-hook:
 	-$(GIT) archive --format=tar HEAD -- src/clientversion.cpp | $(AMTAR) -C $(top_distdir) -xf -
 
+if TARGET_WINDOWS
 $(BITCOIN_WIN_INSTALLER): all-recursive
 	$(MKDIR_P) $(top_builddir)/release
 	STRIPPROG="$(STRIP)" $(INSTALL_STRIP_PROGRAM) $(BITCOIND_BIN) $(top_builddir)/release
@@ -90,6 +91,9 @@ $(BITCOIN_WIN_INSTALLER): all-recursive
 	  echo error: could not build $@
 	@echo built $@
 
+deploy: $(BITCOIN_WIN_INSTALLER)
+endif
+
 if TARGET_DARWIN
 $(OSX_APP)/Contents/PkgInfo:
 	$(MKDIR_P) $(@D)
@@ -167,10 +171,6 @@ appbundle: $(OSX_APP_BUILT)
 deploy: $(OSX_DMG)
 endif
 
-if TARGET_WINDOWS
-deploy: $(BITCOIN_WIN_INSTALLER)
-endif
-
 $(BITCOIN_QT_BIN): FORCE
 	$(MAKE) -C src qt/$(@F)