Fix sanitizer flags for vortex-ffi doctests in CI

[joseph-isaacs]

Summary

When running vortex-ffi tests with sanitizers enabled in CI, doctests were failing due to an ABI mismatch. Doctests are compiled by rustdoc, which reads RUSTDOCFLAGS rather than RUSTFLAGS. Without the sanitizer flags in RUSTDOCFLAGS, the doctest harness was built with different compiler settings than its dependencies, causing rustc to reject the ABI mismatch.

This change mirrors the sanitizer flags to RUSTDOCFLAGS so the doctest harness is built with the same -Zsanitizer value as its dependencies.

Testing

The fix will be validated by the existing rust-instrumented CI workflow, which runs the vortex-ffi tests with sanitizers enabled. The doctests should now compile and run successfully without ABI mismatch errors.

https://claude.ai/code/session_01F3PLB1BLD38qjmBezhSZQd

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚡ 12 improved benchmarks
❌ 6 regressed benchmarks
✅ 1501 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	bitwise_not_vortex_buffer_mut[128]	216.9 ns	275.3 ns	-21.19%
❌	Simulation	bitwise_not_vortex_buffer_mut[1024]	278.6 ns	336.9 ns	-17.31%
❌	Simulation	chunked_varbinview_opt_canonical_into[(1000, 10)]	191.4 µs	227.8 µs	-16%
❌	Simulation	chunked_varbinview_opt_into_canonical[(1000, 10)]	205.7 µs	242 µs	-15.01%
❌	Simulation	bitwise_not_vortex_buffer_mut[2048]	342.2 ns	400.6 ns	-14.56%
❌	Simulation	take_map[(0.1, 0.5)]	993.6 µs	1,125.5 µs	-11.72%
⚡	Simulation	chunked_bool_canonical_into[(1000, 10)]	46.9 µs	32 µs	+46.91%
⚡	Simulation	compare[6]	79.5 µs	70 µs	+13.46%
⚡	Simulation	compare[6]	79.2 µs	70 µs	+13.24%
⚡	Simulation	compare[6]	80.8 µs	71.5 µs	+13.1%
⚡	Simulation	chunked_varbinview_canonical_into[(100, 100)]	311.3 µs	276.2 µs	+12.72%
⚡	Simulation	encode_varbin[(1000, 4)]	161.5 µs	144.1 µs	+12.01%
⚡	Simulation	encode_varbin[(1000, 32)]	168.3 µs	150.4 µs	+11.92%
⚡	Simulation	encode_varbin[(1000, 8)]	162.2 µs	145.2 µs	+11.74%
⚡	Simulation	compare[5]	75.4 µs	67.9 µs	+11.09%
⚡	Simulation	compare[5]	76 µs	68.5 µs	+10.93%
⚡	Simulation	compare[5]	77.1 µs	69.6 µs	+10.77%
⚡	Simulation	chunked_varbinview_into_canonical[(100, 100)]	363.2 µs	328.2 µs	+10.66%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing claude/fervent-hopper-7hi48e (0c4b3e4) with develop (d650cab)}