t9362-mw-to-git-utf8.sh: use the $( ... ) construct for command substitution

The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.

The backquoted form is the traditional method for command
substitution, and is supported by POSIX.  However, all but the
simplest uses become complicated quickly.  In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.

The patch was generated by:

for _f in $(find . -name "*.sh")
do
   sed -i 's@`\(.*\)`@$(\1)@g' ${_f}
done

and then carefully proof-read.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/mw-to-git/t/t9362-mw-to-git-utf8.sh

@@ -70,8 +70,8 @@ test_expect_success 'The shallow option works with accents' '
 	test_path_is_file mw_dir_4/Main_Page.mw &&
 	(
 		cd mw_dir_4 &&
-		test `git log --oneline Néoà.mw | wc -l` -eq 1 &&
-		test `git log --oneline Main_Page.mw | wc -l ` -eq 1
+		test $(git log --oneline Néoà.mw | wc -l) -eq 1 &&
+		test $(git log --oneline Main_Page.mw | wc -l ) -eq 1
 	) &&
 	wiki_check_content mw_dir_4/Néoà.mw Néoà &&
 	wiki_check_content mw_dir_4/Main_Page.mw Main_Page