Merge branch 'nd/attr-match-optim-more'

Start laying the foundation to build the "wildmatch" after we can
agree on its desired semantics.

* nd/attr-match-optim-more:
  attr: more matching optimizations from .gitignore
  gitignore: make pattern parsing code a separate function
  exclude: split pathname matching code into a separate function
  exclude: fix a bug in prefix compare optimization
  exclude: split basename matching code into a separate function
  exclude: stricten a length check in EXC_FLAG_ENDSWITH case

diff --cc Documentation/gitattributes.txt
Simple merge

diff --cc attr.c
Simple merge

diff --cc dir.c
Simple merge

diff --cc t/t0003-attributes.sh
Simple merge