Allow remote to update individual arch triple components

[fjricci]

Summary

If we determine an OS from the executable, but not an environment,
the existing code will not update the target triple to add an
environment provided by the remote.

This manifests if we have an android exe, where we could parse
arm-*-linux from the ELF, but then the remote gives a triple of
arm-*-linux-android. The existing code will not update the
environment in this case, because the OS has not changed.

[fjricci]

Doesn't appear necessary after applying http://reviews.llvm.org/D18620

source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

if (GetID() != LLDB_INVALID_PROCESS_ID)
                 else
                 {
                     // Fill in what is missing in the triple
                     const llvm::Triple &remote_triple = process_arch.GetTriple();
                     llvm::Triple new_target_triple = target_arch.GetTriple();
                     if (new_target_triple.getVendorName().size() == 0)
                     {
                         new_target_triple.setVendor (remote_triple.getVendor());
-
-                        if (new_target_triple.getOSName().size() == 0)
-                        {
-                            new_target_triple.setOS (remote_triple.getOS());
+                    }
 
-                            if (new_target_triple.getEnvironmentName().size() == 0)
-                                new_target_triple.setEnvironment (remote_triple.getEnvironment());
-                        }
+                    }
+                    {
 
-                        ArchSpec new_target_arch = target_arch;
-                        new_target_arch.SetTriple(new_target_triple);
-                        GetTarget().SetArchitecture(new_target_arch);
-                    }
-                }
 
                 if (log)
                     log->Printf ("ProcessGDBRemote::%s final target arch after adjustments for remote architecture: %s %s",
                                  __FUNCTION__,
                                  target_arch.GetArchitectureName () ? target_arch.GetArchitectureName () : "<null>",
                                  target_arch.GetTriple().getTriple ().c_str() ? target_arch.GetTriple().getTriple ().c_str() : "<null>");
             }
             else