fixed XArchEvalUnix using wrong memeber, string_format using c++11 (which we're not ready for yet), code style (indentation and new lines)

src/lib/arch/unix/XArchUnix.cpp

@@ -25,8 +25,8 @@
 //
 
 std::string
-XArchEvalUnix::eval() const throw()
+XArchEvalUnix::eval() const
 {
 	// FIXME -- not thread safe
-	return strerror(m_errno);
+	return strerror(m_error);
 }