Various compiler bug-fixes. MPC seems to run correctly now.

Various compiler bug-fixes.  MPC seems to run correctly now.
* lisp/files.el (lexical-binding): Add a safe-local-variable property.

* lisp/emacs-lisp/byte-opt.el (byte-inline-lapcode): Check how many elements
are added to the stack.
(byte-compile-splice-in-already-compiled-code): Don't touch lexical nor
byte-compile-depth now that byte-inline-lapcode does it for us.
(byte-compile-inline-expand): Don't inline dynbind byte code into
lexbind code, since it has to be done differently.

* lisp/emacs-lisp/bytecomp.el (byte-compile-arglist-warn):
Correctly extract arglist from `closure's.
(byte-compile-cl-warn): Compiler-macros are run earlier now.
(byte-compile-top-level): Bind byte-compile-lexical-environment to nil,
except for lambdas.
(byte-compile-form): Don't run the compiler-macro expander here.
(byte-compile-let): Merge with byte-compile-let*.
Don't preserve-body-value if the body's value was discarded.

* lisp/emacs-lisp/cconv.el (cconv--set-diff, cconv--set-diff-map)
(cconv--map-diff, cconv--map-diff-elem, cconv--map-diff-set): New funs.
(cconv--env-var): New constant.
(cconv-closure-convert-rec): Use it and use them.  Fix a typo that
ended up forgetting to remove entries from lmenvs in `let'.
For `lambda' use the outer `fvrs' when building the closure and don't
forget to remove `vars' from the `emvrs' and `lmenvs' of the body.

* lisp/emacs-lisp/cl-macs.el (cl-byte-compile-block): Disable optimization
in lexbind, because it needs a different implementation.

* src/bytecode.c (exec_byte_code): Fix handling of &rest.

* src/eval.c (Vinternal_interpreter_environment): Remove.
(syms_of_eval): Do declare Vinternal_interpreter_environment as
a global lisp var, but unintern it to hide it.
(Fcommandp):
* src/data.c (Finteractive_form): Understand `closure's.