LibDebug: Keep track of 'prologue end'

This LineProgram instruction is emitted by Clang. Although we currently
have no use for it (it's mostly a debugger feature), we need to handle
this opcode, as otherwise CrashReporter wouldn't work.

Userland/Libraries/LibDebug/Dwarf/LineProgram.h

@@ -181,6 +181,7 @@ private:
     size_t m_file_index { 0 };
     bool m_is_statement { false };
     bool m_basic_block { false };
+    bool m_prologue_end { false };
 
     Vector<LineInfo> m_lines;
 };