workspace: add dosfstools

This adds dosfstools for its FAT32 fsck which is going to be used for
the FAT32 integration tests.

Change-Id: Ie4ae13ad3a63581868fea69fa7d91a27044f1d3b
Reviewed-on: https://review.monogon.dev/c/monogon/+/842
Tested-by: Jenkins CI
Reviewed-by: Sergiusz Bazanski <serge@monogon.tech>
diff --git a/third_party/dosfstools/external.bzl b/third_party/dosfstools/external.bzl
new file mode 100644
index 0000000..459f725
--- /dev/null
+++ b/third_party/dosfstools/external.bzl
@@ -0,0 +1,14 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+def dosfstools_external(name, version):
+    sums = {
+        "c888797b1d84ffbb949f147e3116e8bfb2e145a7": "4a40b488c0c259c11fb54783fc6f01e5ee912582bb49d33d0d11b11f85a42e8d",
+    }
+
+    http_archive(
+        name = name,
+        sha256 = sums[version],
+        strip_prefix = "dosfstools-" + version,
+        build_file = "@//third_party/dosfstools:dosfstools.bzl",
+        urls = ["https://github.com/dosfstools/dosfstools/archive/%s.zip" % (version)],
+    )