fpos_t invalid operands to binary

[manuqiao]

writer.c: In function ‘get_file_size_by_name’: writer.c:116:18: error: invalid operands to binary - (have ‘fpos_t’ {aka ‘struct _G_fpos_t’} and ‘fpos_t’ {aka ‘struct _G_fpos_t’}) 116 | return fpos_end - fpos_begin;