Remove duplicate DFPlatform.h include.
Remove duplicate DFPlatform.h include.

* DocFormats/core/src/lib/DFFilesystem.c
    Remove duplicate DFPlatform.h include.

corinthia/corinthia-docformats,corinthia/corinthia-docformats,corinthia/corinthia-docformats,corinthia/corinthia-docformats,corinthia/corinthia-docformats