github: fake pkg_install

.github/workflows/build-pkgin-tags.yml

@@ -37,6 +37,11 @@ jobs:
             bmake
             bmake DESTDIR=/tmp/destdir install
           )
+          # Generate fake pkg_install binaries, they will never be used.
+          for prog in pkg_add pkg_admin pkg_create pkg_delete pkg_info; do
+            touch /tmp/${prog}
+            chmod +x /tmp/${prog}
+          done
       - name: Build each tag
         run: |
           mkdir bin