asan: prepare for ASAN-friendly ibuf

ASAN-friendly implementation poisons memory after allocation with
ibuf_alloc so we need to fix existing places in code where we access
memory after allocation.

Part of ibuf implementation is inline functions in headers. Thus ibuf
implementation in Lua reimplement this parts. We add poison to these
inline functions in ASAN-friedly implementation so we need add same poison
in Lua implementation.

Part of #7327

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