Fix Bug 20400

[chaoren]

Summary

http://llvm.org/bugs/show_bug.cgi?id=20400

The default triple of i686-pc-linux-gnu for 32 bit linux targets is compatible
but not necessarily identical to the inferior binaries.

Applying Azat Khuzhin's solution of using ArchSpec::IsCompatibleMatch() instead
of ArchSpec::IsExactMatch() when comparing ObjectFile and Modules architecture.

[sylvestre.ledru]

Is it possible to write a test for this to make sure it does not regress? Thanks

[chaoren]

I don't think that would be necessary, since every existing test that
launches an inferior would be broken by a regression.

[clayborg]

Looks fine.

source/Core/Module.cpp

 bool
 Module::SetArchitecture (const ArchSpec &new_arch)
 {
     if (!m_arch.IsValid())
     {
         m_arch = new_arch;
         return true;
     }    
-    return m_arch.IsExactMatch(new_arch);
+    return m_arch.IsCompatibleMatch(new_arch);
 }
 
 bool 
 Module::SetLoadAddress (Target &target, lldb::addr_t value, bool value_is_offset, bool &changed)
 {
     ObjectFile *object_file = GetObjectFile();
     if (object_file)
     {