t/t7005-editor: change from skip_all=* to prereq skip

Change this test to skip test with test prerequisites, and to do setup
work in tests. This improves the skipped statistics on platforms where
the test isn't run.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7005-editor.sh

@@ -111,13 +111,13 @@ do
 	'
 done
 
-if ! echo 'echo space > "$1"' > "e space.sh"
+if echo 'echo space > "$1"' > "e space.sh"
 then
-	skip_all="Skipping; FS does not support spaces in filenames"
-	test_done
+	# FS supports spaces in filenames
+	test_set_prereq SPACES_IN_FILENAMES
 fi
 
-test_expect_success 'editor with a space' '
+test_expect_success SPACES_IN_FILENAMES 'editor with a space' '
 
 	chmod a+x "e space.sh" &&
 	GIT_EDITOR="./e\ space.sh" git commit --amend &&
@@ -126,7 +126,7 @@ test_expect_success 'editor with a space' '
 '
 
 unset GIT_EDITOR
-test_expect_success 'core.editor with a space' '
+test_expect_success SPACES_IN_FILENAMES 'core.editor with a space' '
 
 	git config core.editor \"./e\ space.sh\" &&
 	git commit --amend &&