Revert "ignored function with undeclared options on old environment like centos5"

This reverts commit 343833bc8cc69f097450eb96bcb14762b906024b.
CURLOPT_SEEKFUNCTION and CURLOPT_SEEKDATA is only supported by curl-7.17 later
Merge pull request #214 from hsbt/revise-centos5-support

Revise to support CentOS5