compile all of base/; some arbitrary changes; more "fixes" to `link'

* module/language/scheme/translate.scm (lookup-transformer): When
  expanding syncase macros, use the eval closure from the ghil-env.
  Probably doesn't make any difference whatsoever.

* module/system/base/Makefile.am (SOURCES): Compile pmatch.scm, now that
  it works :-))

* module/system/base/compile.scm (compile-in): Compile inside a
  save-module-excursion, so that side effects of evaluation don't leak
  out.

* module/system/base/pmatch.scm: Change from :use-syntax/:export-syntax
  to simply :use-modules/:export. Also probably has no effect.

* module/system/il/ghil.scm (fix-ghil-mod!): Suppress warnings resulting
  from compilation of define-module.

* src/vm_loader.c (link): So, referencing variables defined but not
  exported from the current module didn't work. Fixed that, but it's
  hacky. There are still some uncaught cases.

module/system/base/pmatch.scm

@@ -1,6 +1,6 @@
 (define-module (system base pmatch)
-  #:use-syntax (ice-9 syncase)
-  #:export-syntax (pmatch ppat))
+  #:use-module (ice-9 syncase)
+  #:export (pmatch ppat))
 ;; FIXME: shouldn't have to export ppat...
 
 ;; Originally written by Oleg Kiselyov. Taken from: