Volatile-qualify a dozen variables in plpython.c to eliminate warnings

from old versions of gcc.  It's not clear to me that this is really
necessary for correctness, but less warnings are always good.
Per buildfarm results and local testing.

src/pl/plpython/plpython.c

 /**********************************************************************
  * plpython.c - python as a procedural language for PostgreSQL
  *
- *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.101 2007/05/31 15:13:05 petere Exp $
+ *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.102 2007/07/13 04:57:59 tgl Exp $
  *
  *********************************************************************
  */
@@ -1714,7 +1714,7 @@ PLyMapping_ToTuple(PLyTypeInfo * info, PyObject * mapping)
 	HeapTuple	tuple;
 	Datum	   *values;
 	char	   *nulls;
-	int			i;
+	volatile int i;
 
 	Assert(PyMapping_Check(mapping));
 
@@ -1729,8 +1729,8 @@ PLyMapping_ToTuple(PLyTypeInfo * info, PyObject * mapping)
 	for (i = 0; i < desc->natts; ++i)
 	{
 		char	   *key;
-		PyObject   *value,
-				   *so;
+		PyObject   * volatile value,
+				   * volatile so;
 
 		key = NameStr(desc->attrs[i]->attname);
 		value = so = NULL;
@@ -1794,7 +1794,7 @@ PLySequence_ToTuple(PLyTypeInfo * info, PyObject * sequence)
 	HeapTuple	tuple;
 	Datum	   *values;
 	char	   *nulls;
-	int			i;
+	volatile int i;
 
 	Assert(PySequence_Check(sequence));
 
@@ -1818,8 +1818,8 @@ PLySequence_ToTuple(PLyTypeInfo * info, PyObject * sequence)
 	nulls = palloc(sizeof(char) * desc->natts);
 	for (i = 0; i < desc->natts; ++i)
 	{
-		PyObject   *value,
-				   *so;
+		PyObject   * volatile value,
+				   * volatile so;
 
 		value = so = NULL;
 		PG_TRY();
@@ -1876,7 +1876,7 @@ PLyObject_ToTuple(PLyTypeInfo * info, PyObject * object)
 	HeapTuple	tuple;
 	Datum	   *values;
 	char	   *nulls;
-	int			i;
+	volatile int i;
 
 	desc = lookup_rowtype_tupdesc(info->out.d.typoid, -1);
 	if (info->is_rowtype == 2)
@@ -1889,8 +1889,8 @@ PLyObject_ToTuple(PLyTypeInfo * info, PyObject * object)
 	for (i = 0; i < desc->natts; ++i)
 	{
 		char	   *key;
-		PyObject   *value,
-				   *so;
+		PyObject   * volatile value,
+				   * volatile so;
 
 		key = NameStr(desc->attrs[i]->attname);
 		value = so = NULL;
@@ -2473,13 +2473,14 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, long limit)
 	PG_TRY();
 	{
 		char	   *nulls = palloc(nargs * sizeof(char));
+		volatile int j;
 
-		for (i = 0; i < nargs; i++)
+		for (j = 0; j < nargs; j++)
 		{
 			PyObject   *elem,
 					   *so;
 
-			elem = PySequence_GetItem(list, i);
+			elem = PySequence_GetItem(list, j);
 			if (elem != Py_None)
 			{
 				so = PyObject_Str(elem);
@@ -2492,10 +2493,10 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, long limit)
 				{
 					char	   *sv = PyString_AsString(so);
 
-					plan->values[i] =
-						InputFunctionCall(&(plan->args[i].out.d.typfunc),
+					plan->values[j] =
+						InputFunctionCall(&(plan->args[j].out.d.typfunc),
 										  sv,
-										  plan->args[i].out.d.typioparam,
+										  plan->args[j].out.d.typioparam,
 										  -1);
 				}
 				PG_CATCH();
@@ -2506,17 +2507,17 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, long limit)
 				PG_END_TRY();
 
 				Py_DECREF(so);
-				nulls[i] = ' ';
+				nulls[j] = ' ';
 			}
 			else
 			{
 				Py_DECREF(elem);
-				plan->values[i] =
-					InputFunctionCall(&(plan->args[i].out.d.typfunc),
+				plan->values[j] =
+					InputFunctionCall(&(plan->args[j].out.d.typfunc),
 									  NULL,
-									  plan->args[i].out.d.typioparam,
+									  plan->args[j].out.d.typioparam,
 									  -1);
-				nulls[i] = 'n';
+				nulls[j] = 'n';
 			}
 		}
 
@@ -2527,6 +2528,8 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, long limit)
 	}
 	PG_CATCH();
 	{
+		int		k;
+
 		MemoryContextSwitchTo(oldcontext);
 		PLy_error_in_progress = CopyErrorData();
 		FlushErrorState();
@@ -2534,13 +2537,13 @@ PLy_spi_execute_plan(PyObject * ob, PyObject * list, long limit)
 		/*
 		 * cleanup plan->values array
 		 */
-		for (i = 0; i < nargs; i++)
+		for (k = 0; k < nargs; k++)
 		{
-			if (!plan->args[i].out.d.typbyval &&
-				(plan->values[i] != PointerGetDatum(NULL)))
+			if (!plan->args[k].out.d.typbyval &&
+				(plan->values[k] != PointerGetDatum(NULL)))
 			{
-				pfree(DatumGetPointer(plan->values[i]));
-				plan->values[i] = PointerGetDatum(NULL);
+				pfree(DatumGetPointer(plan->values[k]));
+				plan->values[k] = PointerGetDatum(NULL);
 			}
 		}