Hi,

This patch adds a command 'keep-variable'. The command takes one single 
parameter - a convenience variable.

This variable is then protected from being deleted by the symbol-file 
command. In order to achieve this it must patch up the type information 
after the symbol table has changed. If the type cannot be fixed up then 
a warning is given and the value is lost. Lazy fixup means that this 
only happens if the variable is actually accessed.

If the keep-variable is never used then variables work exactly as before.

I feel certain that there is something somebody will not like about this 
implementation, but I hope we can sort it out.

The patch requires that my endian fixup patch has been applied first. 
The context in the patch assumes the init-if-undefined has been applied 
first, although the patch is not actually dependent.

Thanks

Andrew Stubbs