Use all the available inline capacity in SwitchTargets

[panstromek]

SmallVec always has at least 16 bytes of inline capacity available on 64bit platforms, so there's no reason to not use it if we can.

[panstromek]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: d50696f (d50696f425d85afd6aefdefd88e41350487ff1d1)
Base parent: d39561c (d39561c2d2b55985d3b6331cc52403e038e7fc8b)

[rust-timer]

Finished benchmarking commit (d50696f): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (primary 6.8%, secondary 2.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	6.8%	[3.7%, 9.8%]	2
Regressions ❌ (secondary)	2.1%	[0.9%, 3.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	6.8%	[3.7%, 9.8%]	2

Cycles

This perf run didn't have relevant results for this metric.

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 487.649s -> 487.104s (-0.11%)
Artifact size: 389.89 MiB -> 389.90 MiB (0.00%)