Merge branch 'rs/grep-p'

* rs/grep-p:
  grep: simplify -p output
  grep -p: support user defined regular expressions
  grep: add option -p/--show-function
  grep: handle pre context lines on demand
  grep: print context hunk marks between files
  grep: move context hunk mark handling into show_line()
  userdiff: add xdiff_clear_find_func()

diff.c

@@ -1603,6 +1603,7 @@ static void builtin_diff(const char *name_a,
 			free(mf1.ptr);
 		if (textconv_two)
 			free(mf2.ptr);
+		xdiff_clear_find_func(&xecfg);
 	}
 
  free_ab_and_return: