cmake XERCES_HAVE_GETCPUID examples

apache/xerces-c cmake/XercesSSE2.cmake :74

check_cxx_source_compiles("
#include <cpuid.h>

int main() {
  unsigned int eax, ebx, ecx, edx;
  __get_cpuid (1, &eax, &ebx, &ecx, &edx);
  return 0;
}"
    XERCES_HAVE_GETCPUID)