BUG: Fix compile-time test of POPCNT #19074
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The compile-time test of POPCNT, cpu_popcnt.c produced code that would execute without error even if the machine didn't support the popcnt instruction. This patch attempts to use popcnt on random numbers so the compiler can't substitute the answer at compile time.
_builtin_popcount is always available, so the compile-time check always succeeds.
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Backport of #19071.
The compile-time test of POPCNT, cpu_popcnt.c produced code that would
execute without error even if the machine didn't support the popcnt
instruction. This patch changes the test so that it attempts to use popcnt on
random numbers so the compiler can't substitute the answer at compile
time. Resolves issue #19067.