GenerateExportHeader: Allow use of of this macro with MODULEs.

The significant issue with MODULEs is that on Windows, the exported
symbols must be dllexported and they are not imported.

In other export macro implementations this is done by defining an
export macro outside of any ifdef which depends on definitions set
on the command line. However, with cmake we already expect the
DEFINE_SYMBOL to be defined, so the regular EXPORT macro can be
used by such plugins.
Merge topic 'geh-MODULE-export' into next

7ffef50 GenerateExportHeader: Allow use of of this macro with MODULEs.
Exclude Borland from this test.

It seems to use characters which do not work well with it.
Merge topic 'geh-cleanup-identifiers' into next

25ca6e1 Exclude Borland from this test.