[ExecutionContext] Return the target/process byte order.

Currently ExecutionContext::GetByteOrder() always returns the host byte
order. This seems like a simple mistake: the return keyword appears to
have been omitted by accident. This patch fixes that and adds a unit
test.

Bugreport: https://llvm.org/PR37950

Differential revision: https://reviews.llvm.org/D48704

llvm-svn: 368181
diff --git a/lldb/source/Target/ExecutionContext.cpp b/lldb/source/Target/ExecutionContext.cpp
index 7732737..a24a098 100644
--- a/lldb/source/Target/ExecutionContext.cpp
+++ b/lldb/source/Target/ExecutionContext.cpp
@@ -183,9 +183,9 @@
 
 lldb::ByteOrder ExecutionContext::GetByteOrder() const {
   if (m_target_sp && m_target_sp->GetArchitecture().IsValid())
-    m_target_sp->GetArchitecture().GetByteOrder();
+    return m_target_sp->GetArchitecture().GetByteOrder();
   if (m_process_sp)
-    m_process_sp->GetByteOrder();
+    return m_process_sp->GetByteOrder();
   return endian::InlHostByteOrder();
 }