build: add #!chezscheme to generated .sls wrappers for Chez syntax extensions

ober

d0d1f3241f2cfde008ef2cbfef9e0abe947b91fd

diff --git a/support/wrap-ss-to-sls.py b/support/wrap-ss-to-sls.py
index 54a6541..1b89b5e 100644
--- a/support/wrap-ss-to-sls.py
+++ b/support/wrap-ss-to-sls.py
@@ -210,6 +210,7 @@ def wrap_file(ss_path, src_dir, lib_dir):
     if prefix_text:
         parts.append(prefix_text)
         parts.append('')
+    parts.append(f"#!chezscheme")
     parts.append(f"(library {lib_name}")
     parts.append(f"  {export_text}")
     parts.append(f"  {import_text}{body_text}")