[lldb] Add missing initialization (NFC)

lldb/include/lldb/Target/StackFrameRecognizer.h

diff --git a/lldb/include/lldb/Target/StackFrameRecognizer.h b/lldb/include/lldb/Target/StackFrameRecognizer.h
index 8acebc1..2f5c5ca 100644
--- a/lldb/include/lldb/Target/StackFrameRecognizer.h
+++ b/lldb/include/lldb/Target/StackFrameRecognizer.h
@@ -146,7 +146,7 @@
   };
 
   std::deque<RegisteredEntry> m_recognizers;
-  uint16_t m_generation;
+  uint16_t m_generation = 0;
 };
 
 /// \class ValueObjectRecognizerSynthesizedValue