Rewrite raw pointers reported by clang plugin (see #3239)

Found using a CEF build with clang_use_chrome_plugins=true
and treat_warnings_as_errors=false.

This change rewrites remaining raw pointers reported by
chromium-rawptr checker and fixes a build error reported
by StackAllocatedChecker.

libcef/common/request_impl.h

@@ -258,7 +258,7 @@ class CefPostDataElementImpl : public CefPostDataElement {
   Type type_ = PDE_TYPE_EMPTY;
   union {
     struct {
-      void* bytes;
+      RAW_PTR_EXCLUSION void* bytes;
       size_t size;
     } bytes;
     cef_string_t filename;