Fix some "variable 'foo' set but not used" warnings

gcc-8 diagnoses these.

llvm-svn: 356378
diff --git a/lldb/source/API/SBTarget.cpp b/lldb/source/API/SBTarget.cpp
index 96bb807..c168ae0 100644
--- a/lldb/source/API/SBTarget.cpp
+++ b/lldb/source/API/SBTarget.cpp
@@ -2356,7 +2356,6 @@
   Log *expr_log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
 #endif
   SBValue expr_result;
-  ExpressionResults exe_results = eExpressionSetupError;
   ValueObjectSP expr_value_sp;
   TargetSP target_sp(GetSP());
   StackFrame *frame = NULL;
@@ -2383,8 +2382,7 @@
           expr, options.GetFetchDynamicValue(),
           frame_description.GetString().str().c_str());
 #endif
-      exe_results =
-          target->EvaluateExpression(expr, frame, expr_value_sp, options.ref());
+      target->EvaluateExpression(expr, frame, expr_value_sp, options.ref());
 
       expr_result.SetSP(expr_value_sp, options.GetFetchDynamicValue());
     }