Ensure correct license detection of pdfium

[pombredanne]

See attached:

unicode.txt

[pombredanne]

The issues are:

• agg23 (Anti-Grain Geometry 2.3) license note
• FreeType license preamble
• openjpeg license note
• libjpeg turbo, also in:
  • https://github.com/libjpeg-turbo/libjpeg-turbo/blob/main/LICENSE.md with only two license
  • and in https://github.com/libjpeg-turbo/libjpeg-turbo/blob/465a9fe0cbee6a6c34d827668e71fab322100241/README-turbo.txt#L31 and https://github.com/libjpeg-turbo/libjpeg-turbo/blob/465a9fe0cbee6a6c34d827668e71fab322100241/LICENSE.txt with three licenses
• IJG (Independent JPEG Group) legal information
• UNICODE LICENSE V3