Speculative fix of Windows build (take 2)

Remove PERFETTO_EXPORT from ScopedResource as the class
is fully defined inline and has no symbols.
This seems to create problems when instantiating it in an
anonymous namespace on Windows:

From https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket/8828353581767219057/+/u/compile__with_patch_/stdout
../../third_party/perfetto/include\perfetto/ext/base/scoped_file.h(54,23): error: 'perfetto::base::ScopedResource<void *, &perfetto::base::ListFilesRecursive(const std::string &, std::vector<std::string> &)::(anonymous class)::__invoke, nullptr, false, perfetto::base::PlatformHandleChecker>' must have external linkage when declared 'dllexport'
class PERFETTO_EXPORT ScopedResource {
                      ^

Change-Id: I264973225637b60de52fe0d963c1dc1bc7741b75
diff --git a/include/perfetto/ext/base/scoped_file.h b/include/perfetto/ext/base/scoped_file.h
index 5a99de6..53d21b1 100644
--- a/include/perfetto/ext/base/scoped_file.h
+++ b/include/perfetto/ext/base/scoped_file.h
@@ -51,7 +51,7 @@
           T InvalidValue,
           bool CheckClose = true,
           class Checker = internal::DefaultValidityChecker<T, InvalidValue>>
-class PERFETTO_EXPORT ScopedResource {
+class ScopedResource {
  public:
   using ValidityChecker = Checker;
   static constexpr T kInvalid = InvalidValue;