Don't tell the linker about available_externally definitions. If we do, it will
complain about duplicated definitions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124634 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/lto/LTOModule.cpp b/tools/lto/LTOModule.cpp
index 59c8b35..e2ecabc 100644
--- a/tools/lto/LTOModule.cpp
+++ b/tools/lto/LTOModule.cpp
@@ -304,6 +304,10 @@
   if (def->getName().startswith("llvm."))
     return;
 
+  // ignore available_externally
+  if (def->hasAvailableExternallyLinkage())
+    return;
+
   // string is owned by _defines
   const char *symbolName = ::strdup(mangler.getNameWithPrefix(def).c_str());