build failure in PHP 8.1

[Joungkyun]

In PHP 8.1, mod_magic fails to build.

libtool: compile:  cc -std=gnu99 -I. -I/root/work/github/php/mod_magic -I/root/work/github/php/mod_magic/include -I/root/work/github/php/mod_magic/main -I/root/work/github/php/mod_magic -I/opt/php-qa/php81/include/php -I/opt/php-qa/php81/include/php/main -I/opt/php-qa/php81/include/php/TSRM -I/opt/php-qa/php81/include/php/Zend -I/opt/php-qa/php81/include/php/ext -I/opt/php-qa/php81/include/php/ext/date/lib -DHAVE_CONFIG_H -g -O2 -DZEND_COMPILE_DL_EXT=1 -c /root/work/github/php/mod_magic/magic.c -MMD -MF magic.dep -MT magic.lo  -fPIC -DPIC -o .libs/magic.o
In file included from /opt/php-qa/php81/include/php/main/fopen_wrappers.h:21:0,
                 from /opt/php-qa/php81/include/php/main/php.h:419,
                 from /root/work/github/php/mod_magic/magic.c:49:
/root/work/github/php/mod_magic/magic.c: In function 'magic_set_error':
/opt/php-qa/php81/include/php/main/php_globals.h:29:29: error: 'struct _php_core_globals' has no member named 'log_errors_max_len'
 # define PG(v) (core_globals.v)
                             ^
/root/work/github/php/mod_magic/magic.c:164:35: note: in expansion of macro 'PG'
  buffer_len = vspprintf (&buffer, PG(log_errors_max_len), format, args);
                                   ^
/root/work/github/php/mod_magic/magic.c:218:24: warning: assignment from incompatible pointer type [enabled by default]
   PG (last_error_file) = strdup (ZSTR_VAL (zend_get_compiled_filename ()));
                        ^
/root/work/github/php/mod_magic/magic.c:221:24: warning: assignment from incompatible pointer type [enabled by default]
   PG (last_error_file) = strdup (zend_get_executed_filename ());
                        ^
make: *** [magic.lo] 오류 1

1. Since PHP 8.1, removed log_errors_max_len ini entry
2. change proto type of PG(last_error_file) to (zend_string *) from (char *)