(COMPILED): Rename to CLOSURE

(COMPILED): Rename to CLOSURE

In preparation for the use of `PVEC_COMPILED` objects for
interpreted functions, rename them to use a more neutral name.

* src/lisp.h (enum pvec_type): Rename `PVEC_COMPILED` to `PVEC_CLOSURE`.
(enum Lisp_Compiled): Use `CLOSURE_` prefix i.s.o `COMPILED_`.
Also use `CODE` rather than `BYTECODE`.
(CLOSUREP): Rename from `COMPILEDP`.
(enum Lisp_Closure): Rename from `Lisp_Compiled`.

* src/alloc.c, src/bytecode.c, src/comp.c, src/data.c, src/eval.c,
* src/fns.c, src/lisp.h, src/lread.c, src/pdumper.c, src/print.c,
* src/profiler.c: Rename all uses accordingly.
* src/.gdbinit (xclosure): Rename from `xcompiled`.
(xcompiled): New obsolete alias.
(xpr): Adjust accordingly.  Also adjust to new PVEC_CLOSURE tag name.