NetworkTracePoller: fix a warning by explicitly capturing 'this'

Without this:
packages/modules/Connectivity/service-t/native/libs/libnetworkstats/NetworkTracePoller.cpp:42:35: warning: implicit capture of 'this' with a capture default of '=' is deprecated [-Wdeprecated-this-capture]
   42 |   runner->PostDelayedTask([=]() { PollAndSchedule(runner, poll_ms); }, poll_ms);
      |                                   ^
packages/modules/Connectivity/service-t/native/libs/libnetworkstats/NetworkTracePoller.cpp:42:28: note: add an explicit capture of 'this' to capture '*this' by reference
   42 |   runner->PostDelayedTask([=]() { PollAndSchedule(runner, poll_ms); }, poll_ms);
      |                            ^
      |                             , this

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I703f2e33948c226c43e170abc793b8a58438eccf
diff --git a/service-t/native/libs/libnetworkstats/NetworkTracePoller.cpp b/service-t/native/libs/libnetworkstats/NetworkTracePoller.cpp
index 450f380..241d5fa 100644
--- a/service-t/native/libs/libnetworkstats/NetworkTracePoller.cpp
+++ b/service-t/native/libs/libnetworkstats/NetworkTracePoller.cpp
@@ -39,7 +39,7 @@
                                          uint32_t poll_ms) {
   // Always schedule another run of ourselves to recursively poll periodically.
   // The task runner is sequential so these can't run on top of each other.
-  runner->PostDelayedTask([=]() { PollAndSchedule(runner, poll_ms); }, poll_ms);
+  runner->PostDelayedTask([=, this]() { PollAndSchedule(runner, poll_ms); }, poll_ms);
 
   if (mMutex.try_lock()) {
     ConsumeAllLocked();