Fix uninitialized uninitialized boolean

Author: chios202

mlir/lib/Query/Matcher/VariantValue.cpp

@@ -172,7 +172,7 @@ void VariantValue::setSigned(int64_t newValue) {
 // Boolean
 bool VariantValue::isBoolean() const { return type == ValueType::Boolean; }
 
-bool VariantValue::getBoolean() const { return value.Signed; }
+bool VariantValue::getBoolean() const { return value.Boolean; }
 
 void VariantValue::setBoolean(bool newValue) {
   type = ValueType::Boolean;