Fix compilation issue on older Erlang releases.
Fix compilation issue on older Erlang releases.

If `binary_to_float` is not exported, the compiler thinks we are
calling a local function, which fails to compile.

chaptastic/erlydtl,kivra/erlydtl,alexr/erlydtl,project-fifo/erlydtl,wrw/erlydtl,truqu/erlydtl,campanja-forks/erlydtl,wrw/erlydtl,A40in/erlydtl,huangered/erlydtl,oxpa/erlydtl,kivra/erlydtl,quasiconvex/erlydtl,wrw/erlydtl,oxpa/erlydtl,alexr/erlydtl,aerosol/erlydtl,project-fifo/erlydtl,huangered/erlydtl,chaptastic/erlydtl,A40in/erlydtl,chaptastic/erlydtl,A40in/erlydtl,truqu/erlydtl,aerosol/erlydtl,aerosol/erlydtl,alexr/erlydtl,huangered/erlydtl,truqu/erlydtl,kivra/erlydtl,campanja-forks/erlydtl,campanja-forks/erlydtl,quasiconvex/erlydtl,quasiconvex/erlydtl,oxpa/erlydtl,erlydtl/erlydtl,erlydtl/erlydtl,project-fifo/erlydtl,erlydtl/erlydtl