cmake HAS_VLD1 examples

AcademySoftwareFoundation/openexr cmake/OpenEXRSetup.cmake :413

check_c_source_compiles("#include <arm_neon.h>
int main() {
  float a[] = {1.0, 1.0};
  vld1q_f32_x2(a);
  return 0;
}" HAS_VLD1)