Add ExternalTypeInfoProvider the the key of the ReflectionContext TypeInfo cache

This change is analogous to the TypeInfo cache in TypeLowering, which does the
exact same thing. In LLDB the ExternalTypeInfoProvider may gain new information
throughout the life of a process, and more importantly, it may return
context-dependent results.

rdar://122432501

Author: adrian-prantl

include/swift/RemoteInspection/ReflectionContext.h

@@ -122,7 +122,10 @@ class ReflectionContext
   using super::readMetadata;
   using super::readObjCClassName;
   using super::readResolvedPointerValue;
-  llvm::DenseMap<typename super::StoredPointer, const RecordTypeInfo *> Cache;
+  llvm::DenseMap<std::pair<typename super::StoredPointer,
+                           remote::TypeInfoProvider::IdType>,
+                 const RecordTypeInfo *>
+      Cache;
 
   /// All buffers we need to keep around long term. This will automatically free them
   /// when this object is destroyed.
@@ -892,7 +895,8 @@ class ReflectionContext
   getMetadataTypeInfo(StoredPointer MetadataAddress,
                       remote::TypeInfoProvider *ExternalTypeInfo) {
     // See if we cached the layout already
-    auto found = Cache.find(MetadataAddress);
+    auto ExternalTypeInfoId = ExternalTypeInfo ? ExternalTypeInfo->getId() : 0;
+    auto found = Cache.find({MetadataAddress, ExternalTypeInfoId});
     if (found != Cache.end())
       return found->second;
 
@@ -922,7 +926,7 @@ class ReflectionContext
     }
 
     // Cache the result for future lookups
-    Cache[MetadataAddress] = TI;
+    Cache[{MetadataAddress, ExternalTypeInfoId}] = TI;
     return TI;
   }