util: Add Nix shell file

Add a Nix shell file which is able to compile flashrom.

Change-Id: I9757b952f4b034e98c2b4b70fbede52d8efb9d50
Signed-off-by: Felix Singer <felix.singer@secunet.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/58012
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

util/shell.nix

@@ -0,0 +1,16 @@
+with import <nixpkgs> {};
+
+stdenv.mkDerivation {
+	name = "flashrom";
+
+	buildInputs = [
+		cmocka
+		libftdi1
+#		libjaylink	# Will be added in NixOS 21.11
+		libusb1
+		meson
+		ninja
+		pciutils
+		pkg-config
+	];
+}