Fixed an issue in the platform options where if no architecture was specified where the platform would fail to select itself with something like:

(lldb) platfrom select remote-ios



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@156626 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Interpreter/OptionGroupPlatform.cpp b/source/Interpreter/OptionGroupPlatform.cpp
index 8602ca8..e6d4e7f 100644
--- a/source/Interpreter/OptionGroupPlatform.cpp
+++ b/source/Interpreter/OptionGroupPlatform.cpp
@@ -34,7 +34,7 @@
         platform_sp = Platform::Create (m_platform_name.c_str(), error);
         if (platform_sp)
         {
-            if (!platform_sp->IsCompatibleArchitecture(arch, &platform_arch))
+            if (platform_arch.IsValid() && !platform_sp->IsCompatibleArchitecture(arch, &platform_arch))
             {
                 error.SetErrorStringWithFormat("platform '%s' doesn't support '%s'", platform_sp->GetName(), arch.GetTriple().getTriple().c_str());
                 platform_sp.reset();