[cleanup] remove trailing whitespace from source code files

example/conversion_use_case.cpp

@@ -1,4 +1,4 @@
-//  endian/example/conversion_use_case.cpp 
+//  endian/example/conversion_use_case.cpp
 
 //  Copyright Beman Dawes 2014
 
@@ -47,5 +47,5 @@ int main()
     out_rec.balance = boost::endian::native_to_big(out_rec.balance);  // reverse if needed
     out.write((const char*)&out_rec, sizeof(out_rec));
   }
-    
+
 }