Improve correctness and consistency of 'eval-when' usage.

* module/ice-9/boot-9.scm:
* module/ice-9/i18n.scm:
* module/ice-9/poll.scm:
* module/ice-9/popen.scm:
* module/ice-9/r6rs-libraries.scm:
* module/oop/goops.scm:
* module/oop/goops/compile.scm:
* module/oop/goops/dispatch.scm:
* module/srfi/srfi-88.scm:
* module/system/foreign.scm:
* module/texinfo/serialize.scm: Change most uses of 'compile' to
  'expand', except where we must avoid it during initial bootstrap
  before the module system is loaded.  Remove redundant uses of
  'compile' where 'expand' is also given.  Standardize on the
  "(expand load eval)" order of conditions.

module/srfi/srfi-88.scm

@@ -35,7 +35,7 @@
 
 ;; Change the keyword syntax both at compile time and run time; the latter is
 ;; useful at the REPL.
-(eval-when (compile load)
+(eval-when (expand load eval)
   (read-set! keywords 'postfix))
 
 (define (keyword->string k)