revert error message assignment for older versions
revert error message assignment for older versions

as errstr is only available since version > 2.2

irtnog/ModSecurity,csanders-git/ModSecurity,p0pr0ck5/ModSecurity,p0pr0ck5/ModSecurity,p0pr0ck5/ModSecurity,irtnog/ModSecurity,bjh7242/ModSecurity,phpModSecurity/ModSecurity,marcstern/ModSecurity,marcstern/ModSecurity,bjh7242/ModSecurity,bjh7242/ModSecurity,bjh7242/ModSecurity,csanders-git/ModSecurity,irtnog/ModSecurity,marcstern/ModSecurity,bjh7242/ModSecurity,marcstern/ModSecurity,irtnog/ModSecurity,p0pr0ck5/ModSecurity,csanders-git/ModSecurity,p0pr0ck5/ModSecurity,csanders-git/ModSecurity,csanders-git/ModSecurity,marcstern/ModSecurity,csanders-git/ModSecurity,bjh7242/ModSecurity,p0pr0ck5/ModSecurity,irtnog/ModSecurity,irtnog/ModSecurity