[ORC] Create a new SymbolStringPool by default in ExecutionSession constructor.

This makes the common case of constructing an ExecutionSession tidier.

llvm-svn: 329013
diff --git a/llvm/unittests/ExecutionEngine/Orc/LegacyAPIInteropTest.cpp b/llvm/unittests/ExecutionEngine/Orc/LegacyAPIInteropTest.cpp
index 6c7384a..db29024 100644
--- a/llvm/unittests/ExecutionEngine/Orc/LegacyAPIInteropTest.cpp
+++ b/llvm/unittests/ExecutionEngine/Orc/LegacyAPIInteropTest.cpp
@@ -18,9 +18,8 @@
 
 TEST(LegacyAPIInteropTest, QueryAgainstVSO) {
 
-  SymbolStringPool SP;
-  ExecutionSession ES(SP);
-  auto Foo = SP.intern("foo");
+  ExecutionSession ES(std::make_shared<SymbolStringPool>());
+  auto Foo = ES.getSymbolStringPool().intern("foo");
 
   VSO V;
   SymbolMap Defs;