don't expand directories on a terminal negation extglob

[hong4rc]

Fixes #188. With the default expandDirectories: true, a pattern ending in a negation extglob returns the files it should exclude — glob(['loc/**/!(en.po)']) hands back every en.po.

The issue is labeled upstream, but picomatch is correct: picomatch('loc/**/!(en.po)')('loc/one/en.po') is false. The bug is in tinyglobby's own normalizePattern, which appends /** to any pattern not ending in * — so loc/**/!(en.po) becomes loc/**/!(en.po)/**, and now !(en.po) matches the directory while the trailing /** re-adds en.po underneath. Running the same glob with expandDirectories: false returns the correct result, confirming the append is the cause.

The fix skips the /** append when the final segment is a negation extglob. It's deliberately narrow — only a terminal !(...) — so loc/**/!(en).po and other forms still expand as before.