Correctly macroexpand top-level forms during eager macroexpand

Correctly macroexpand top-level forms during eager macroexpand

* lisp/emacs-lisp/byte-run.el (eval-when-compile, eval-and-compile):
Improve docstrings.

* lisp/emacs-lisp/macroexp.el (internal-macroexpand-for-load): Add
`full-p' parameter; when nil, call `macroexpand' instead of
`macroexpand-all'.

* src/lread.c (readevalloop_eager_expand_eval): New function
that can recurse into toplevel forms.
(readevalloop): Call it.
* src/lisp.h: Declare Qprogn.
* src/callint.c (Qprogn): No longer static.

* test/automated/bytecomp-tests.el (test-byte-comp-compile-and-load):
Add compile flag.
(test-byte-comp-macro-expansion)
(test-byte-comp-macro-expansion-eval-and-compile)
(test-byte-comp-macro-expansion-eval-when-compile)
(test-byte-comp-macro-expand-lexical-override): Use it.
(test-eager-load-macro-expansion)
(test-eager-load-macro-expansion-eval-and-compile)
(test-eager-load-macro-expansion-eval-when-compile)
(test-eager-load-macro-expand-lexical-override): New tests.