Add a generic rule for installing files

Makefile.lib

@@ -3,11 +3,23 @@ default: all
 
 # Include Autoconf variables.
 Makefile.config: Makefile.config.in
-	./config.status
+	./config.status --file $@
 
 include Makefile.config
 
 
+# Installing stuff.
+define install-file-in =
+
+  install:: $(1)/$(notdir $(2))
+
+  $(1)/$(notdir $(2)): $(2)
+	install -d $(1)
+	install -t $(1) $(2)
+
+endef
+
+
 # Include all sub-Makefiles.
 define include_sub_makefile =
   d := $$(patsubst %/, %, $$(dir $(1)))

corepkgs/Makefile.new

@@ -0,0 +1,3 @@
+corepkgs_FILES = nar.nix buildenv.nix buildenv.pl unpack-channel.nix derivation.nix fetchurl.nix imported-drv-to-derivation.nix
+
+$(foreach file,config.nix $(corepkgs_FILES),$(eval $(call install-file-in,$(datadir)/nix/corepkgs,$(d)/$(file))))