Fix a memory leak introduced in ee4512ed48 (trace2: create new
combined trace facility, 2019-02-22), we were doing a free() of other
memory allocated in tr2tls_create_self(), but not the "thread_name"
"struct strbuf".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Acked-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>