A fix for Bug#9443 "mysql_client_test fails on linux and some solaris

platforms": yet another issue with floating pointer comparisons.
The fix uses the workaround with volatiles.

sql/item_cmpfunc.cc

@@ -393,10 +393,16 @@ int Arg_comparator::compare_e_binary_string()
 
 int Arg_comparator::compare_real()
 {
-  double val1= (*a)->val();
+  /*
+    Fix yet another manifestation of Bug#2338. 'Volatile' will instruct
+    gcc to flush double values out of 80-bit Intel FPU registers before
+    performing the comparison.
+  */
+  volatile double val1, val2;
+  val1= (*a)->val();
   if (!(*a)->null_value)
   {
-    double val2= (*b)->val();
+    val2= (*b)->val();
     if (!(*b)->null_value)
     {
       owner->null_value= 0;