The GCC documentation states that, as of GCC 2.7.2, these aren't
necessary for proper program behavior. The documentation further
discourages their use because they don't suppress unnecessary code
duplication.
The Panda codebase these days uses "extern template class" instead,
which tells the compiler not to perform implicit template expansion
because an explicit template expansion is available for linking
elsewhere in the program. This is a more compiler-neutral way of
achieving the same thing as '#pragma interface', making
'#pragma interface' not only redundant, it could also mask problems
in the "extern template class" machinery.
