Fix GitHub Actions build on macOS

- Install gnu getopt
- Replace egrep with grep -E (not necessary?)

- Try explicitly setting excludes to an array

   Otherwise, if it is unset, it appears that (at least on macos), the following
   expands to an empty string argument rather than no arguments:

       "${excludes[@]}"

.github/workflows/test.yml

@@ -58,7 +58,7 @@ jobs:
     - name: Byte compilation
       run: emacs --eval "(setq byte-compile-error-on-warn (>= emacs-major-version 26))" -L . --batch -f batch-byte-compile ./*.el
     - name: Tests
-      run: nix shell ${{ matrix.ledger_version || 'nixpkgs#ledger' }} --print-build-logs -c ./makem.sh test -vv
+      run: nix shell 'nixpkgs#getopt' ${{ matrix.ledger_version || 'nixpkgs#ledger' }} --print-build-logs -c ./makem.sh test -vv
     # This is currently for information only, since a lot of docstrings need fixing up
     - name: Checkdoc
       run: make lint-checkdoc || true

makem.sh

@@ -406,7 +406,7 @@ function files-project {
     # matching that pattern with "git ls-files".  Excludes submodules.
     [[ $1 ]] && pattern="/$1" || pattern="."
 
-    local excludes
+    local excludes=()
     for submodule in $(submodules)
     do
         excludes+=(":!:$submodule")
@@ -424,7 +424,7 @@ function dirs-project {
 function files-project-elisp {
     # Echo list of Elisp files in project.
     files-project 2>/dev/null \
-        | egrep "\.el$" \
+        | grep -E "\.el$" \
         | filter-files-exclude-default \
         | filter-files-exclude-args
 }