add <primcall> to tree-il

add <primcall> to tree-il

* libguile/expand.c:
* libguile/expand.h (SCM_EXPANDED_PRIMCALL_TYPE_NAME):
  (SCM_EXPANDED_PRIMCALL_FIELD_NAMES):
  (SCM_EXPANDED_PRIMCALL_SRC):
  (SCM_EXPANDED_PRIMCALL_NAME):
  (SCM_EXPANDED_PRIMCALL_ARGS):
  (SCM_MAKE_EXPANDED_PRIMCALL): Add "primcall" Tree-IL type.

* doc/ref/compiler.texi (Tree-IL): Update docs.

* libguile/memoize.c (memoize): Memoizer for primcalls.

* module/ice-9/psyntax.scm: Build primcalls, sometimes.  Also change
  build-primref to just make a primitive-ref.

* module/language/tree-il.scm: Add primcall to the exports, parsers,
  serializers, etc.

* module/language/tree-il/analyze.scm:
* module/language/tree-il/compile-glil.scm:
* module/language/tree-il/fix-letrec.scm:
* module/language/tree-il/inline.scm:
* module/language/tree-il/primitives.scm:
* module/language/elisp/compile-tree-il.scm: Add primcall support.

* test-suite/tests/tree-il.test: Use primcalls sometimes.