Update version to CPAN version 0.9928

Update version to CPAN version 0.9928

[DELTA]

0.9927
  * Released 0.99_26 as 0.9927

0.99_26
  * Add usage error to pure-perl vcmp
  * Quote version classname in test for 5.8 compatability
  * Use base instead of parent for tests
  * Update ppport.h for future compatibility

0.99_25
  * Fix stack usage in vcmp method
  * Drop Perl 5.5 compatibility
  * Use PERL_VERSION_GE for Perl 7 compatibility
  * Fix typo in pod example for comparing versions.