Fix -Wunused-result warnings in LLDB

These try_lock usages intentionally ignore the result, as commented.

Similar to 4d23764ddd, which was reviewed
previously.

lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetItemInfoHandler.cpp

@@ -106,7 +106,7 @@ void AppleGetItemInfoHandler::Detach() {
       m_get_item_info_return_buffer_addr != LLDB_INVALID_ADDRESS) {
     std::unique_lock<std::mutex> lock(m_get_item_info_retbuffer_mutex,
                                       std::defer_lock);
-    lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
+    (void)lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
     m_process->DeallocateMemory(m_get_item_info_return_buffer_addr);
   }
 }

lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetPendingItemsHandler.cpp

@@ -109,7 +109,7 @@ void AppleGetPendingItemsHandler::Detach() {
       m_get_pending_items_return_buffer_addr != LLDB_INVALID_ADDRESS) {
     std::unique_lock<std::mutex> lock(m_get_pending_items_retbuffer_mutex,
                                       std::defer_lock);
-    lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
+    (void)lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
     m_process->DeallocateMemory(m_get_pending_items_return_buffer_addr);
   }
 }

lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetQueuesHandler.cpp

@@ -107,7 +107,7 @@ void AppleGetQueuesHandler::Detach() {
       m_get_queues_return_buffer_addr != LLDB_INVALID_ADDRESS) {
     std::unique_lock<std::mutex> lock(m_get_queues_retbuffer_mutex,
                                       std::defer_lock);
-    lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
+    (void)lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
     m_process->DeallocateMemory(m_get_queues_return_buffer_addr);
   }
 }

lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp

@@ -115,7 +115,7 @@ void AppleGetThreadItemInfoHandler::Detach() {
       m_get_thread_item_info_return_buffer_addr != LLDB_INVALID_ADDRESS) {
     std::unique_lock<std::mutex> lock(m_get_thread_item_info_retbuffer_mutex,
                                       std::defer_lock);
-    lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
+    (void)lock.try_lock(); // Even if we don't get the lock, deallocate the buffer
     m_process->DeallocateMemory(m_get_thread_item_info_return_buffer_addr);
   }
 }