Constify functions taking char *

Constify functions taking char *

* alloc.c (pending_malloc_warning, malloc_warning): Add const.
* callproc.c (relocate_fd, getenv_internal_1, getenv_internal)
(egetenv): Likewise.
* doprnt.c (doprnt): Likewise.
* editfns.c (set_time_zone_rule, format2): Likewise.
* emacs.c (decode_env_path): Likewise.
* eval.c (signal_error, error): Likewise.
* insdel.c (replace_range_2): Likewise.
* keyboard.c (cmd_error_internal): Likewise.
* lread.c (isfloat_string, make_symbol, dir_warning): Likewise.
* print.c (write_string, write_string_1, print_error_message):
Likewise.
* vm-limit.c (warn_function, memory_warnings): Likewise.
* xdisp.c (message1, message1_nolog, message_with_string)
(vmessage, message, message_nolog): Likewise.
* emacs.c: Remove duplicate declaration.
* keyboard.h: Likewise.
* lisp.h: Update prototypes.