Lazily load the controlling macros for all of the headers known in the
PCH file. In the Cocoa-prefixed "Hello, World" benchmark, this takes
us from reading 503 identifiers down to 37 and from 470 macros down to
4. It also results in an 8% performance improvement.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70094 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/IdentifierTable.cpp b/lib/Basic/IdentifierTable.cpp
index 344c4eb..8b74b20 100644
--- a/lib/Basic/IdentifierTable.cpp
+++ b/lib/Basic/IdentifierTable.cpp
@@ -42,6 +42,8 @@
 
 IdentifierInfoLookup::~IdentifierInfoLookup() {}
 
+ExternalIdentifierLookup::~ExternalIdentifierLookup() {}
+
 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
                                  IdentifierInfoLookup* externalLookup)
   : HashTable(8192), // Start with space for 8K identifiers.