layers: Eliminate compiler warnings on Windows.

This includes suppressing compiler warning C4065, where VS complains if a
switch statement has a "default", but not "case" statements.  This was true in
many functions of the auto-generated "helper" header files.

This also includes removing unreferenced local variables, and dealing with some
type differences (sometimes with casting, sometimes with changing the type).
diff --git a/layers/mem_tracker.cpp b/layers/mem_tracker.cpp
index 8f1961c..de5ef19 100644
--- a/layers/mem_tracker.cpp
+++ b/layers/mem_tracker.cpp
@@ -1008,7 +1008,7 @@
     size_t              *pDataSize,
     void                *pData)
 {
-    // This entrypoint is NOT going to init its own dispatch table since loader calls here early
+    /* This entrypoint is NOT going to init it's own dispatch table since loader calls here early */
     VkExtensionProperties *ext_props;
     uint32_t *count;
 
@@ -1136,7 +1136,7 @@
             sprintf(str, "Unknown Queue %p", queue);
             layerCbMsg(VK_DBG_MSG_ERROR, VK_VALIDATION_LEVEL_0, queue, 0, MEMTRACK_INVALID_QUEUE, "MEM", str);
         } else {
-            for (int i = 0; i < count; i++) {
+            for (uint32_t i = 0; i < count; i++) {
                 if (pQueueInfo->pMemRefList.size() > 0) {
                     for (list<VkDeviceMemory>::iterator it = pQueueInfo->pMemRefList.begin(); it != pQueueInfo->pMemRefList.end();) {
                         if ((*it) == pMems[i]) {
diff --git a/vk_helper.py b/vk_helper.py
index 8104b2f..3f16c3d 100755
--- a/vk_helper.py
+++ b/vk_helper.py
@@ -1336,6 +1336,9 @@
     def _generateSHHeader(self):
         header = []
         header.append('#pragma once\n')
+        header.append('#ifdef _WIN32\n')
+        header.append('#pragma warning( disable : 4065 )\n')
+        header.append('#endif\n')
         header.append('#include <%s>\n\n\n' % self.in_file)
         return "\n".join(header)