DWARF: Reset the state after parsing a line table prologue and remove an unnecessary lookup.

llvm-svn: 139859
diff --git a/llvm/lib/DebugInfo/DWARFDebugLine.cpp b/llvm/lib/DebugInfo/DWARFDebugLine.cpp
index 94fff65..d8200a0 100644
--- a/llvm/lib/DebugInfo/DWARFDebugLine.cpp
+++ b/llvm/lib/DebugInfo/DWARFDebugLine.cpp
@@ -200,6 +200,8 @@
   const uint32_t end_offset = debug_line_offset + prologue->TotalLength +
                               sizeof(prologue->TotalLength);
 
+  state.reset();
+
   while (*offset_ptr < end_offset) {
     uint8_t opcode = debug_line_data.getU8(offset_ptr);