find_stray_empty_lines: fix tail "invalid context" error

"tail -1" works only with one input file. Using it with multiple input
files throws following error on Ubuntu systems:

tail: option used in invalid context

Adding "-n" makes it work on all cases.

Signed-off-by: Javier Viguera <javier.viguera@digi.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

scripts/find_stray_empty_lines

@@ -7,7 +7,7 @@ grep -n -B1 -r $'^\t*}' . | grep -A1 '.[ch]-[0-9]*-$'
 grep -n -A1 -r $'^\t*{' . | grep -B1 '.[ch]-[0-9]*-$'
 
 # find trailing empty lines
-find -type f | xargs tail -1 | while read file; do
+find -type f | xargs tail -n1 | while read file; do
         test x"$file" = x"" && continue
         read lastline
         #echo "|$file|$lastline"