check_v46: does not remove leading spaces from perf data

[paulboot]

Some plugins, like check_ssh, add a leading space to the perf data and check_v46 should remove this space or the prepended ipv4_a1_ and ipv6_a1_ will have a trailing space and service-perfdata scripts will fail to parse the performance data because of too many spaces.

See Pull request for check_v46 with a proposed fix for this issue.