Disable 2 warnings occurring in release builds

Because of using a jump in an asm block there is a warning regarding
disabling global optimisations (for that function only) and as a result of
that another warning about being unable to check for buffer overruns. To
work around the warnings temporarily disable both (C4740 and C4748).

Regression since e405bf1607.

src/msw/stackwalk.cpp

@@ -306,6 +306,18 @@ void wxStackWalker::WalkFromException(size_t maxDepth)
 
 #endif // wxUSE_ON_FATAL_EXCEPTION
 
+#ifdef __VISUALC__
+    #pragma warning(push)
+
+    // "warning C4740: flow in or out of inline asm code suppresses global
+    //  optimization"
+    #pragma warning(disable: 4740)
+
+    // "warning C4748: /GS can not protect parameters and local variables from
+    //  local buffer overrun because optimizations are disabled in function"
+    #pragma warning(disable: 4748)
+#endif
+
 void wxStackWalker::Walk(size_t skip, size_t maxDepth)
 {
     // This code is based on frames.cpp from Edd Dawson's dbg library
@@ -348,5 +360,9 @@ void wxStackWalker::Walk(size_t skip, size_t maxDepth)
     WalkFrom(&ctx, skip, maxDepth);
 }
 
+#ifdef __VISUALC__
+    #pragma warning(pop)
+#endif
+
 #endif // wxUSE_STACKWALKER