Removed checks for antique Borland versions

VTK already assumes elsewhere that __BORLANDC__ >= 0x0560, so
remove remaining checks.

Change-Id: I3425d6a3aa07bd9b52dee5918f2d2010dd5ee0a7
Merge topic 'borland-cleanup' into master

116f93f8 Removed checks for antique Borland versions