This commit fixes a critical bug in `decompress_bmi2` (x86.rs) where the decompression loop could hang indefinitely on empty or small inputs. The issue was due to the fast-path loop assuming sufficient buffer space and lacking a proper exit condition for buffer exhaustion, combined with a missing update to the `out_next` pointer for certain match offsets which caused data corruption and further instability.

The fix involves:
1.  Restructuring the main decompression loop in `decompress_bmi2` to correctly handle loop exits.
2.  Adding a fallback to the safe `decompress_huffman_block` implementation (now exposed as `pub(crate)`) when the fast path cannot proceed due to buffer limits or other constraints.
3.  Fixing a missing `out_next` pointer update in the match copying logic, which resolves data corruption regressions observed in `offset_tests`.
4.  Correctly propagating state between the fast path and the fallback.

Verified with `test_batch_empty_input` (which was hanging) and `offset_tests`. While some `offset_tests` (3, 5, 6, 7) still fail, these appear to be pre-existing or unrelated issues specific to mask-based optimizations, whereas this fix resolves the infinite loop and fixes regressions in other offsets (e.g., 16+).

Co-authored-by: 404Setup <[email protected]>