(ENCODE_ISO_CHARACTER_DIMENSION1): Pay attention to

(ENCODE_ISO_CHARACTER_DIMENSION1): Pay attention to
CODING_FLAG_ISO_SAFE.
(ENCODE_ISO_CHARACTER_DIMENSION2): Likewise.
(safe_terminal_coding): New variable.
(Fset_safe_terminal_coding_system_internal): New function.
(init_coding_once): Initilize safe_terminal_coding.
(syms_of_coding): Declare set-safe-terminal-coding-system as a
Lisp function.
(Vmicrosoft_code_table): New variable.
(syms_of_coding): Declare it as a Lisp variable and initialize it.
(detect_coding_mask): Pay attention to Vmicrosoft_code_table.