[PATCH] t/aggregate-results: fix paste(1) invocation

["D. Ben Knoble" <ben.knoble+github@gmail.com>]

When running `make test`, when missing prereqs the following is emitted:

    make aggregate-results
    usage: paste [-s] [-d delimiters] file ...
    fixed   1
    success 30066
    failed  0
    broken  218
    total   31274

POSIX says that `paste` requires a file operand; stdin was clearly
intended by 49da404070 (test-lib: show missing prereq summary,
2021-11-20). Use it.

Signed-off-by: D. Ben Knoble <ben.knoble+github@gmail.com>
---

The test results are from a real run but on an as-yet-unpublished commit. Not
sure if worth keeping that part of the message, so feel free to only keep the
"make" and "usage" lines when applying?

 t/aggregate-results.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/aggregate-results.sh b/t/aggregate-results.sh
index 6e3bcc4aec..6cb0ff11de 100755
--- a/t/aggregate-results.sh
+++ b/t/aggregate-results.sh
@@ -44,7 +44,7 @@
 		tr -s "," "\n" |
 		grep -v '^$' |
 		sort -u |
-		paste -s -d ' ')
+		paste -s -d ' ' -)
 	if test -n "$unique_missing_prereq"
 	then
 		printf "\nmissing prereq: $unique_missing_prereq\n\n"
-- 
2.48.1