Otherwise building with cfileio.h would result in:
/usr/include/assimp/cfileio.h:61:58: error: unknown type name ‘aiOrigin’
typedef aiReturn (*aiFileSeek)(C_STRUCT aiFile*, size_t, aiOrigin);
^~~~~~~~
/usr/include/assimp/cfileio.h:64:9: error: unknown type name ‘aiFile’
typedef aiFile* (*aiFileOpenProc) (C_STRUCT aiFileIO*, const char*, const char*);
^~~~~~
/usr/include/assimp/cfileio.h:122:5: error: unknown type name ‘aiFileSeek’
aiFileSeek SeekProc;
^~~~~~~~~~