Free the FPDF_SYSFONTINFO_DEFAULT instead of delete
Free the FPDF_SYSFONTINFO_DEFAULT instead of delete

It was created with FX_Alloc instead of new. So use FX_Free instead of
delete.

BUG=664072

Review-Url: https://codereview.chromium.org/2485383005

DrAlexx/pdfium,DrAlexx/pdfium,DrAlexx/pdfium,DrAlexx/pdfium