stream.hls_playlist: fix some regex pattern & code optimization (#1918)
stream.hls_playlist: fix some regex pattern & code optimization (#1918)

* replace enumerate by iter

Line numbers are no longer required.

* replace regex to precompiled one

it's better because it's high frequently used





melmorabity/streamlink,back-to/streamlink,back-to/streamlink,chhe/streamlink,streamlink/streamlink,wlerin/streamlink,bastimeyer/streamlink,bastimeyer/streamlink,chhe/streamlink,wlerin/streamlink,gravyboat/streamlink,streamlink/streamlink,gravyboat/streamlink,beardypig/streamlink,beardypig/streamlink,melmorabity/streamlink