begin-program takes properties alist

begin-program takes properties alist

* module/system/vm/assembler.scm (assert-match): New helper macro to
  check argument types.
  (<meta>): Add properties field.  Rename name field to "label" to
  indicate that it should be unique.
  (make-meta, meta-name): New helpers.
  (begin-program): Take additional properties argument.
  (emit-init-constants): Adapt to begin-program change.
  (link-symtab): Allow for anonymous procedures.

* test-suite/tests/rtl.test: Adapt tests.