Export the syntax-case compatible splicing-let(rec)-syntax

Author: dpk

lib/chibi/syntax-case.sld

@@ -4,7 +4,8 @@
           datum->syntax syntax->datum
           generate-temporaries with-syntax syntax-violation
           with-ellipsis ellipsis-identifier?
-          define-syntax let-syntax letrec-syntax)
+          define-syntax let-syntax letrec-syntax
+          splicing-let-syntax splicing-letrec-syntax)
   (import (rename (chibi)
                   (define-syntax %define-syntax)
                   (let-syntax %let-syntax)