Unexec removal: Main part

Unexec removal: Main part

* configure.ac: Remove unexec-specific parts.
(EMACS_CONFIG_FEATURES): Always report that we do not have the UNEXEC
feature.
(AC_ECHO): No longer display a line about the unexec feature.
* lisp/loadup.el:
* lisp/startup.el: Remove unexec-specific code.
* src/Makefile.in (base_obj): Drop 'UNEXEC_OBJ'.
* src/alloc.c (staticvec): Never initialize this variable.
(BLOCK_ALIGN): Always allow large blocks.
(mmap_lisp_allowed_p): Remove unexec-specific code.
* src/buffer.c (init_buffer):
* src/conf_post.h (ADDRESS_SANITIZER):
* src/emacs.c (load_pdump, main): Remove unexec-specific code.
(Fdump_emacs): Remove function.
(syms_of_emacs): Remove 'Fdump_emacs'.
* src/lastfile.c: Remove unexec-specific code.
* src/lisp.h (gflags): Remove unexec-specific flags.
(will_dump_p, will_bootstrap_p, will_dump_with_unexec_p)
(dumped_with_unexec_p, definitely_will_not_unexec_p): Remove or adjust
predicates.
(SUBR_SECTION_ATTRIBUTE): Remove unexec-specific definition.
* src/pdumper.c (Fdump_emacs_portable): Remove unexec-specific warning.
* src/process.c (init_process_emacs): Remove !unexec condition
* src/sysdep.c (maybe_disable_address_randomization): Adjust comment.
(init_signals):
* src/timefns.c (init_timefns): Remove unexec-specific code.
* src/w32heap.c (report_temacs_memory_usage): Remove function.
* src/w32heap.h: Adjust comment.
* src/w32image.c (globals_of_w32image): Remove unexec-specific code.

(cherry picked from commit 15e2b14f03796467fab8e8086d293a5813afaa5b)