compilation passes return third value: the continuation environment

* module/system/base/compile.scm: Expect compile passes to produce three
  values, not two. The third is the "continuation environment", the
  environment that can be used to compile a subsequent expression from
  the same source language. For example, expansion-time side effects can
  set the current module, which would be reflected appropriately in the
  continuation environment.

* module/language/assembly/compile-bytecode.scm:
* module/language/bytecode/spec.scm:
* module/language/ecmascript/compile-ghil.scm:
* module/language/ghil/compile-glil.scm:
* module/language/glil/spec.scm:
* module/language/objcode/spec.scm:
* module/language/scheme/compile-ghil.scm:
* module/system/base/compile.scm: Update compile passes to return a
  continuation environment.

module/language/bytecode/spec.scm

@@ -25,7 +25,7 @@
   #:export (bytecode))
 
 (define (compile-objcode x e opts)
-  (values (bytecode->objcode x) e))
+  (values (bytecode->objcode x) e e))
 
 (define (decompile-objcode x e opts)
   (values (objcode->bytecode x) e))