remove C99 which isn't suppored by all compilers yet

--- python3/Modules/_pickle.c.orig	2019-04-03 16:34:01.380124314 +0200
+++ python3/Modules/_pickle.c	2019-04-03 16:35:18.579005171 +0200
@@ -674,9 +674,12 @@
         PyErr_NoMemory();
         return NULL;
     }
-    for (size_t i = 0; i < self->mt_allocated; i++) {
+    {
+    size_t i;
+    for (i = 0; i < self->mt_allocated; i++) {
         Py_XINCREF(self->mt_table[i].me_key);
     }
+    }
     memcpy(new->mt_table, self->mt_table,
            sizeof(PyMemoEntry) * self->mt_allocated);
 
@@ -4204,7 +4207,9 @@
         return NULL;
 
     memo = self->pickler->memo;
-    for (size_t i = 0; i < memo->mt_allocated; ++i) {
+    {
+    size_t i;
+    for (i = 0; i < memo->mt_allocated; ++i) {
         PyMemoEntry entry = memo->mt_table[i];
         if (entry.me_key != NULL) {
             int status;
@@ -4225,6 +4230,7 @@
                 goto error;
         }
     }
+    }
     return new_memo;
 
   error:
@@ -6791,10 +6797,13 @@
         if (new_memo == NULL)
             return -1;
 
-        for (size_t i = 0; i < new_memo_size; i++) {
+        {
+        size_t i;
+        for (i = 0; i < new_memo_size; i++) {
             Py_XINCREF(unpickler->memo[i]);
             new_memo[i] = unpickler->memo[i];
         }
+        }
     }
     else if (PyDict_Check(obj)) {
         Py_ssize_t i = 0;
@@ -6839,7 +6848,8 @@
 
   error:
     if (new_memo_size) {
-        for (size_t i = new_memo_size - 1; i != SIZE_MAX; i--) {
+        size_t i;
+        for (i = new_memo_size - 1; i != SIZE_MAX; i--) {
             Py_XDECREF(new_memo[i]);
         }
         PyMem_FREE(new_memo);