[ORC] Use JITEvaluatedSymbol for IndirectStubsManager findStub and findPointer.

Existing implementations of these methods do not require lazy materialization,
and switching to JITEvaluatedSymbol allows us to remove error checking on the
client side.

llvm-svn: 333835
diff --git a/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp b/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp
index 0d2a712..a1f864b 100644
--- a/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp
+++ b/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp
@@ -36,11 +36,11 @@
     llvm_unreachable("Not implemented");
   }
 
-  JITSymbol findStub(StringRef Name, bool ExportedStubsOnly) override {
+  JITEvaluatedSymbol findStub(StringRef Name, bool ExportedStubsOnly) override {
     llvm_unreachable("Not implemented");
   }
 
-  JITSymbol findPointer(StringRef Name) override {
+  JITEvaluatedSymbol findPointer(StringRef Name) override {
     llvm_unreachable("Not implemented");
   }