t6022: Use -eq not = to test output of wc -l

When comparing numbers such as "3" to "$(wc -l)", we should check for
numerical equality using -eq instead of string equality using = because
some implementations of wc output extra whitespace.

Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>