simplify constant usage. FILEINFO_MIME_TYPE is available since PHP 5.3.0
fixed missing const argument, when passed magic_file argument fails.
Merge branch 'hotfix/4077'

Close #4077
Merge pull request #4102 from sasezaki/validator_fileinfo_simplify_constants

simplify constant usage. FILEINFO_MIME_TYPE is available since PHP 5.3.0
Merge branch 'hotfix/4102' into develop

Forward port #4102