stdlib: Linux build fix

Author: slavapestov

stdlib/public/runtime/Demangle.cpp

@@ -4,8 +4,8 @@
 #include "Private.h"
 
 #if SWIFT_OBJC_INTEROP
-
 #include <objc/runtime.h>
+#endif
 
 // FIXME: This stuff should be merged with the existing logic in
 // include/swift/Reflection/TypeRefBuilder.h as part of the rewrite
@@ -298,5 +298,3 @@ Demangle::NodePointer swift::_swift_buildDemanglingForMetadata(const Metadata *t
   // Not a type.
   return nullptr;
 }
-
-#endif

stdlib/public/runtime/Private.h

@@ -156,9 +156,7 @@ namespace swift {
   const Metadata *
   _searchConformancesByMangledTypeName(const llvm::StringRef typeName);
 
-#if SWIFT_OBJC_INTEROP
   Demangle::NodePointer _swift_buildDemanglingForMetadata(const Metadata *type);
-#endif
 
   /// A helper function which avoids performing a store if the destination
   /// address already contains the source value.  This is useful when