Add a GetDisplayName() API to SBFrame, SBFunction and SBSymbol

This API is currently a no-op (in the sense that it has the same behavior as the already existing GetName()), but is meant long-term to provide a best-for-visualization version of the name of a function

It is still not hooked up to the command line 'bt' command, nor to the 'gui' mode, but I do have ideas on how to make that work going forward

rdar://21203242

llvm-svn: 241482
diff --git a/lldb/source/Symbol/Symbol.cpp b/lldb/source/Symbol/Symbol.cpp
index dff15dd..3e8af2f 100644
--- a/lldb/source/Symbol/Symbol.cpp
+++ b/lldb/source/Symbol/Symbol.cpp
@@ -185,6 +185,14 @@
 }
 
 ConstString
+Symbol::GetDisplayName () const
+{
+    if (!m_mangled)
+        return ConstString();
+    return m_mangled.GetDisplayDemangledName();
+}
+
+ConstString
 Symbol::GetReExportedSymbolName() const
 {
     if (m_type == eSymbolTypeReExported)