libpod: use /var/run instead of /run on FreeBSD

This changes /run to /var/run for .containerenv and secrets in FreeBSD
containers for consistency with FreeBSD path conventions. Running Linux
containers on FreeBSD hosts continue to use /run for compatibility.

[NO NEW TESTS NEEDED]

Signed-off-by: Doug Rabson <dfr@rabson.org>

pkg/specgen/generate/storage_linux.go

@@ -0,0 +1,11 @@
+package generate
+
+import (
+	"context"
+
+	"github.com/containers/common/libimage"
+)
+
+func imageRunPath(ctx context.Context, img *libimage.Image) (string, error) {
+	return "/run", nil
+}