drm_hwcomposer: Hold the lock for executeCommands

The lock for this HWC3 call was missed in the previous HWC3 MR.

Change-Id: I9f9b44f38d28b04779c4ce45085dcec39503f632
Signed-off-by: Drew Davenport <ddavenport@google.com>
diff --git a/hwc3/ComposerClient.cpp b/hwc3/ComposerClient.cpp
index 988e032..e60d9e8 100644
--- a/hwc3/ComposerClient.cpp
+++ b/hwc3/ComposerClient.cpp
@@ -376,6 +376,8 @@
 ndk::ScopedAStatus ComposerClient::executeCommands(
     const std::vector<DisplayCommand>& commands,
     std::vector<CommandResultPayload>* results) {
+  const std::unique_lock lock(hwc_->GetResMan().GetMainLock());
+  DEBUG_FUNC();
   cmd_result_writer_ = std::make_unique<CommandResultWriter>(results);
   for (const auto& cmd : commands) {
     ExecuteDisplayCommand(cmd);