Instead of searching twice to extract and to delete, extract and
delete the found position at the first search.

This makes faster nearly twice, for regexps and strings.

|              |compare-ruby|built-ruby|
|:-------------|-----------:|---------:|
|regexp-short  |      2.143M|    3.918M|
|regexp-long   |    105.162k|  205.410k|
|string-short  |      3.789M|    7.964M|
|string-long   |      1.301M|    2.457M|