Merge branch 'jh/memihash-opt'

Hotfix for a topic that is already in 'master'.

* jh/memihash-opt:
p0004: make perf test executable
t3008: skip lazy-init test on a single-core box
test-online-cpus: helper to return cpu count
name-hash: fix buffer overrun

diff --cc Makefile
Simple merge

diff --cc t/helper/.gitignore
Simple merge