Consistently negate the value from demangling

Author: Azoy

lib/Demangling/Demangler.cpp

@@ -4424,7 +4424,7 @@ NodePointer Demangler::demangleIntegerType() {
   switch (peekChar()) {
   case 'n':
     nextChar();
-    integer = createNode(Node::Kind::NegativeInteger, demangleNatural());
+    integer = createNode(Node::Kind::NegativeInteger, -demangleNatural());
     break;
 
   default:

lib/Demangling/Remangler.cpp

@@ -3972,7 +3972,7 @@ ManglingError Remangler::mangleInteger(Node *node, unsigned int depth) {
 }
 
 ManglingError Remangler::mangleNegativeInteger(Node *node, unsigned int depth) {
-  Buffer << "$n" << node->getIndex();
+  Buffer << "$n" << -node->getIndex();
 
   return ManglingError::Success;
 }

stdlib/public/runtime/MetadataLookup.cpp

@@ -2447,7 +2447,7 @@ class DecodedMetadataBuilder {
   }
 
   TypeLookupErrorOr<BuiltType> createNegativeIntegerType(intptr_t value) {
-    return BuiltType(-value);
+    return BuiltType(value);
   }
 };