[Orc] Add conversion to/from RuntimeDyld::SymbolInfo for JITSymbol.

This tidies up some code that was manually constructing RuntimeDyld::SymbolInfo
instances from JITSymbols. It will save more mess in the future when
JITSymbol::getAddress is extended to return an Expected<TargetAddress> rather
than just a TargetAddress, since we'll be able to embed the error checking in
the conversion.

llvm-svn: 271350
diff --git a/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp b/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp
index 89adb66..87928347 100644
--- a/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp
+++ b/llvm/unittests/ExecutionEngine/Orc/ObjectLinkingLayerTest.cpp
@@ -165,7 +165,7 @@
     createLambdaResolver(
       [&](const std::string &Name) {
         if (auto Sym = ObjLayer.findSymbol(Name, true))
-          return RuntimeDyld::SymbolInfo(Sym.getAddress(), Sym.getFlags());
+          return Sym.toRuntimeDyldSymbol();
         return RuntimeDyld::SymbolInfo(nullptr);
       },
       [](const std::string &Name) {