Fix critical bug on matching regular expressions.
Fix critical bug on matching regular expressions.

Issue:	#186
Reported by:	@moisseev

andrejzverev/rspamd,dark-al/rspamd,dark-al/rspamd,minaevmike/rspamd,dark-al/rspamd,andrejzverev/rspamd,minaevmike/rspamd,amohanta/rspamd,awhitesong/rspamd,AlexeySa/rspamd,AlexeySa/rspamd,andrejzverev/rspamd,AlexeySa/rspamd,amohanta/rspamd,AlexeySa/rspamd,AlexeySa/rspamd,awhitesong/rspamd,minaevmike/rspamd,AlexeySa/rspamd,amohanta/rspamd,AlexeySa/rspamd,minaevmike/rspamd,AlexeySa/rspamd,andrejzverev/rspamd,minaevmike/rspamd,minaevmike/rspamd,minaevmike/rspamd,andrejzverev/rspamd,minaevmike/rspamd,andrejzverev/rspamd,andrejzverev/rspamd,dark-al/rspamd,minaevmike/rspamd,amohanta/rspamd,andrejzverev/rspamd,AlexeySa/rspamd,dark-al/rspamd,awhitesong/rspamd,amohanta/rspamd,awhitesong/rspamd