Fix Clang 22 codegen regression
Clang 22 apparently has a codegen regression in capture() and capture_stage() functions. GCC and the other versions of Clang also showed a marginal speedup which however could be due to noise.
Combined results of two STC tests:
https://tests.stockfishchess.org/tests/view/6a45b104f97ff95f78795570
https://tests.stockfishchess.org/tests/view/6a474aaff97ff95f787957a9
STC (clang++ 22):
LLR: 2.811 (-2.944,2.944) <0.00,2.00>
Ptnml(0-2): 67, 3094, 7975, 3306, 102
Non-regression STC (g++, clang++ ~21):
LLR: 6.617 (-2.944,2.944) <-1.75,0.25>
Ptnml(0-2): 428, 22211, 56555, 22553, 429
Local test results (Zen 4, x86-64-avx512icl, bench 512 1 16, 50 runs):
Clang (22.1.2): PASSED: speedup = +0.0169, P(speedup > 0) = 1.0000
GCC (15.2.0): FAILED: speedup = +0.0031, P(speedup > 0) = 0.9597
closes https://github.com/official-stockfish/Stockfish/pull/6945
No functional change