Merge branch 'rs/include-comments-before-the-function-header'

"git grep -W", "git diff -W" and their friends learned a heuristic to extend a pre-context beyond the line that matches the "function pattern" (aka "diff.*.xfuncname") to include a comment block, if exists, that immediately precedes it. * rs/include-comments-before-the-function-header: grep: show non-empty lines before functions with -W grep: update boundary variable for pre-context t7810: improve check of -W with user-defined function lines xdiff: show non-empty lines before functions with -W xdiff: factor out is_func_rec() t4051: add test for comments preceding function lines