sdk: Make the tracing SDK compatible with MSVC

This patch makes the tracing SDK compile with MSVC. The main changes
are:

1) Working around an issue in the track event trace point where a
   constexpr variable incorrectly loses its constexpr-ness when accessed
   from a lambda.

2) Enabling "standards-compliant" mode with /permissive- to enable a
   fix for a recently addressed compiler bug[1] with explicit template
   member instantiation.

3) Working around another compiler bug[2] with thread_local template
   member instantiation. This bug has yet to be addressed, but the
   workaround doesn't appear to have adverse side-effects as long as
   PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS and
   PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS are used consistently.

The minimum supported compiler version is Visual Studio 2019 v16.5.

Bug: 174454879

[1] https://developercommunity.visualstudio.com/content/problem/319447/explicit-specialization-of-static-data-member-inco.html
[2] https://developercommunity2.visualstudio.com/t/Unable-to-specialize-static-thread_local/130268

Change-Id: I6270e9646e7f02f0d4c881b8d6634c606e981bb0
diff --git a/test/client_api_example.cc b/test/client_api_example.cc
index 62c495d..f8dfcc4 100644
--- a/test/client_api_example.cc
+++ b/test/client_api_example.cc
@@ -88,6 +88,7 @@
 
 }  // namespace
 
+PERFETTO_DECLARE_DATA_SOURCE_STATIC_MEMBERS(MyDataSource);
 PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(MyDataSource);
 
 int main() {