A cmXMLSafe constructor named its parameter 'str' which shadowed the
name of the 'str' method. This renames the parameter to avoid the
conflict warning.
This class provides easy syntax to efficiently insert blocks of data
into XML documents with proper escapes. It replaces the old
cmCTest::MakeXMLSafe and cmSystemTools::MakeXMLSafe methods which
allocated extra memory instead of directly streaming the data.