Simplify NativeProcessProtocol::GetArchitecture/GetByteOrder

Summary:
These functions used to return bool to signify whether they were able to
retrieve the data. This is redundant because the ArchSpec and ByteOrder
already have their own "invalid" states, *and* because both of the
current implementations (linux, netbsd) can always provide a valid
result.

This allows us to simplify bits of the code handling these values.

Reviewers: eugene, krytarowski

Subscribers: javed.absar, lldb-commits

Differential Revision: https://reviews.llvm.org/D39733

llvm-svn: 317779
diff --git a/lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp b/lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
index 5cd4094..71324a4 100644
--- a/lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
@@ -144,14 +144,10 @@
   if (m_reg_context_sp)
     return m_reg_context_sp;
 
-  ArchSpec target_arch;
-  if (!m_process.GetArchitecture(target_arch))
-    return NativeRegisterContextSP();
-
   const uint32_t concrete_frame_idx = 0;
   m_reg_context_sp.reset(
       NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(
-          target_arch, *this, concrete_frame_idx));
+          m_process.GetArchitecture(), *this, concrete_frame_idx));
 
   return m_reg_context_sp;
 }