Fix some more uses of int instead of EMACS_INT.

Fix some more uses of int instead of EMACS_INT.

 font.c (font_intern_prop): Use EMACS_INT for string length
 variables.
 character.c (parse_str_as_multibyte, str_as_multibyte)
 (parse_str_to_multibyte, str_to_multibyte, str_as_unibyte)
 (string_count_byte8, string_escape_byte8): Use EMACS_INT for
 string length arguments, variables, and return values.
 character.h (parse_str_as_multibyte, str_as_multibyte)
 (parse_str_to_multibyte, str_to_multibyte, str_as_unibyte): Adjust
 prototypes.
 fns.c (Fstring_as_multibyte): Use EMACS_INT for string length
 variables.
 alloc.c <total_string_size>: Declare as EMACS_INT, not int.
 (Fmake_string): Protect against too large strings.
 (live_string_p, live_cons_p, live_symbol_p, live_float_p)
 (live_misc_p): Use ptrdiff_t instead of int for pointer
 differences.
 (string_bytes, check_sblock, check_string_free_list)
 (allocate_string_data, compact_small_strings, Fmake_string)
 (Fmake_bool_vector, make_string, make_unibyte_string)
 (make_multibyte_string, make_string_from_bytes)
 (make_specified_string_string, Fmake_list, Fmake_vector): Use
 EMACS_INT for string length variables and arguments.
 (find_string_data_in_pure, make_pure_string, make_pure_c_string)
 (Fpurecopy): Use EMACS_INT for string size.
 (mark_vectorlike, mark_char_table, mark_object): Use EMACS_UINT
 for vector size.
 lisp.h (make_string, make_unibyte_string, make_multibyte_string)
 (make_string_from_bytes, make_specified_string_string)
 (make_pure_string, string_bytes): Adjust prototypes.