Simplified demangle() a little to make better use of RVO.

include/boost/core/demangle.hpp

@@ -93,15 +93,10 @@ inline void demangle_free( char const * name ) BOOST_NOEXCEPT
 inline std::string demangle( char const * name )
 {
     scoped_demangled_name demangled_name( name );
-    char const * const p = demangled_name.get();
-    if( p )
-    {
-        return p;
-    }
-    else
-    {
-        return name;
-    }
+    char const * p = demangled_name.get();
+    if( !p )
+        p = name;
+    return p;
 }
 
 #else