Fix MYSQL Bug#60057 : sel_arg_range_seq_next loops in optimized compilation/VS2010

When mariadb 5.3 is compiler with VS2010, several tests would enter infinite loop in 
sel_arg_range_seq_next(). The reason is compiler backend bug. This bug is not
present in either VS2008  or VS2010 SP1 RC.

Workaround is to compile this function without most aggresive optimization flag
 (-Og )  using #pragma optimize ("g", {on|off}) for this version of MSVC compiler.

sql/opt_range_mrr.cc

@@ -120,6 +120,14 @@ static void step_down_to(SEL_ARG_RANGE_SEQ *arg, SEL_ARG *key_tree)
     TRUE   No more ranges in the sequence
 */
 
+#if (_MSC_FULL_VER == 160030319)
+/*
+   Workaround Visual Studio 2010 RTM compiler backend bug, the function enters 
+   infinite loop.
+ */
+#pragma optimize("g", off)
+#endif
+
 bool sel_arg_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
 {
   SEL_ARG *key_tree;
@@ -273,6 +281,12 @@ walk_up_n_right:
   return 0;
 }
 
+#if (_MSC_FULL_VER == 160030319)
+/* VS2010 compiler bug workaround */
+#pragma optimize("g", on)
+#endif
+
+
 /****************************************************************************
   MRR Range Sequence Interface implementation that walks array<QUICK_RANGE>
  ****************************************************************************/