Avoid __popcnt64 on MSVC Windows 32-bit platform

The `__popcnt64` intrinsic isn't supported on 32-bit Windows, so `__popcnt` should be used instead.

Author: frederick-vs-ja

sqlite-vec.c

@@ -529,7 +529,11 @@ static unsigned int __builtin_popcountl(unsigned int x) {
 }
 #else
 #include <intrin.h>
+#ifdef _WIN64
 #define __builtin_popcountl __popcnt64
+#else
+static unsigned int __builtin_popcountl(u64 n) { return __popcnt((u32)n) + __popcnt((u32)(n >> 32)); }
+#endif
 #endif
 #endif