bpforc.h: Include <optional> header
bpforc.h: Include <optional> header

This is required since this header had std::optional<std::tuple<uint8_t *, uintptr_t>>

Fixes buiild errors with clang-12 with gcc11-runtime

Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>

iovisor/bpftrace,iovisor/bpftrace,iovisor/bpftrace,iovisor/bpftrace