Merge branch 'bc/maint-diff-hunk-header-fix' into maint

Merge branch 'bc/maint-diff-hunk-header-fix' into maint

* bc/maint-diff-hunk-header-fix:
  t4018-diff-funcname: test syntax of builtin xfuncname patterns
  diff hunk pattern: fix misconverted "\{" tex macro introducers
  diff: use extended regexp to find hunk headers
  diff.*.xfuncname which uses "extended" regex's for hunk header selection
  diff.c: associate a flag with each pattern and use it for compiling regex
  diff.c: return pattern entry pointer rather than just the hunk header pattern

Conflicts:
	Documentation/gitattributes.txt