chore: import upstream snapshot with attribution

cmake/checks/cpu_lsx.cpp

@@ -0,0 +1,15 @@
+#include <stdio.h>
+#include <lsxintrin.h>
+
+int test()
+{
+    const float src[] = { 0.0f, 1.0f, 2.0f, 3.0f};
+    v4f32 val = (v4f32)__lsx_vld((const float*)(src), 0);
+    return __lsx_vpickve2gr_w(__lsx_vftint_w_s(val), 3);
+}
+
+int main()
+{
+  printf("%d\n", test());
+  return 0;
+}