diffutils: disable hanging test on x86_64-darwin

The test-c-stack tests hang on x86_64-darwin when they are run under
Rosetta 2. Disabling these tests allows the rest of the tests to run
successfully on that platform.

This is a similar to the issue that affected gnugrep (NixOS#236229).

pkgs/tools/text/diffutils/default.nix

@@ -20,6 +20,13 @@ stdenv.mkDerivation rec {
   /* If no explicit coreutils is given, use the one from stdenv. */
   buildInputs = [ coreutils ];
 
+  # Disable stack-related gnulib tests on x86_64-darwin because they have problems running under
+  # Rosetta 2: test-c-stack hangs, test-sigsegv-catch-stackoverflow fails.
+  postPatch = if (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86_64) then ''
+    sed -i -E 's:test-c-stack2?\.sh::g' gnulib-tests/Makefile.in
+    sed -i -E 's:test-sigsegv-catch-stackoverflow[12]::g' gnulib-tests/Makefile.in
+  '' else null;
+
   configureFlags =
     # "pr" need not be on the PATH as a run-time dep, so we need to tell
     # configure where it is. Covers the cross and native case alike.