Build: update for new deps::. semantics

Now it does not look for a package in the
parent directories, but rather auto-scans
dependencies. (This might change in the
future.)

[ci skip]

tools/build/windows/Makefile

@@ -43,7 +43,7 @@ export PKGFILES := $(patsubst %,lib/%/pak_$(PAKVERSION).zip,$(RVERSIONS))
 deploy:
 	@echo "----- DEPLOYING packages -----------------------------------"
 	@echo $(PKGFILES)
-	R_LIBS=$(RLIB) $(R) -q -e "pak::pkg_install('deps::.', dependencies = 'Config/Needs/deploy')"
+	R_LIBS=$(RLIB) $(R) -q -e "pak::pkg_install('deps::$(PKGROOT)', dependencies = 'Config/Needs/deploy')"
 	R_LIBS=$(RLIB) $(R) -q -e \
 		"pak:::push_packages(strsplit(Sys.getenv('PKGFILES'), ' ')[[1]])"