configure: Use check_builtin() where appropriate

configure

@@ -3317,9 +3317,8 @@ elif enabled sparc; then
 
 elif enabled x86; then
 
-    check_code ld intrin.h "__rdtsc()" && enable rdtsc
-
-    check_code ld mmintrin.h "_mm_empty()" && enable mm_empty
+    check_builtin rdtsc    intrin.h   "__rdtsc()"
+    check_builtin mm_empty mmintrin.h "_mm_empty()"
 
     enable local_aligned_8 local_aligned_16