[fpc-devel] New rules for External

[Peter Vreman]

- Interface declaration has External
  Every implementation declaration will give an error:
  (03210_E_Procedure is already declared EXTERNAL)

- Interface declaration has no External
  Implementation has External
    - For Win32 (maybe OS/2 also?) this is allowed when the import is
      done from a DLL, e.g. "external dllname name 'fsdfds'" or
"cdecl;external dllname"
    - Otherwise it gives an error (because the assembler name becomes
      different from the one already set in the interface)
      (03211_E_Can't declare procedure as EXTERNAL)