tests/multiboot: Fix whitespace failure

Commit b43671f8 accidentally broke run_test.sh within tests/multiboot;
due to a subtle change in whitespace.

These two commands produce theh same output (at least, for sane $IFS
of space-tab-newline):

echo -e "...$@..."
echo -e "...$*..."

But that's only because echo inserts spaces between multiple arguments
(the $@ case), while the $* form gives a single argument to echo with
the spaces already present.

But when converting to printf %b, there are no automatic spaces between
multiple arguments, so we HAVE to use $*.

It doesn't help that run_test.sh isn't part of 'make check'.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/multiboot/run_test.sh

@@ -26,7 +26,7 @@ run_qemu() {
     local kernel=$1
     shift
 
-    printf %b "\n\n=== Running test case: $kernel $@ ===\n\n" >> test.log
+    printf %b "\n\n=== Running test case: $kernel $* ===\n\n" >> test.log
 
     $QEMU \
         -kernel $kernel \