fix dfHeaderPattern for various patterns
fix dfHeaderPattern for various patterns

yyljlyy/mackerel-agent,mackerelio/mackerel-agent,mackerelio/mackerel-agent,mackerelio/mackerel-agent,kamatama41/mackerel-agent,kamatama41/mackerel-agent,stanaka/mackerel-agent,stanaka/mackerel-agent,kamatama41/mackerel-agent,yyljlyy/mackerel-agent,yyljlyy/mackerel-agent,kamatama41/mackerel-agent,stanaka/mackerel-agent,stanaka/mackerel-agent,yyljlyy/mackerel-agent