* Add a -I flag to the Perl bindings to nix-build and some other

scripts.
* Include the version and architecture in the -I flag so that there is
  at least a chance that a Nix binary built for one Perl version will
  run on another version.

scripts/copy-from-other-stores.pl.in

@@ -1,4 +1,4 @@
-#! @perl@ -w
+#! @perl@ -w @perlFlags@
 
 use strict;
 use File::Basename;

scripts/nix-build.in

@@ -1,4 +1,4 @@
-#! @perl@ -w -I@libexecdir@/nix
+#! @perl@ -w @perlFlags@
 
 use strict;
 use Nix::Config;

scripts/nix-channel.in

@@ -1,4 +1,4 @@
-#! @perl@ -w
+#! @perl@ -w -I@libexecdir@/nix
 
 use strict;
 use Nix::Config;

scripts/nix-collect-garbage.in

@@ -1,4 +1,4 @@
-#! @perl@ -w
+#! @perl@ -w @perlFlags@
 
 use strict;
 use Nix::Config;

scripts/nix-install-package.in

@@ -1,4 +1,4 @@
-#! @perl@ -w
+#! @perl@ -w @perlFlags@
 
 use strict;
 use File::Temp qw(tempdir);