perf script: force stdin for flamegraph in live mode

JIRA: https://issues.redhat.com/browse/RHEL-87957

upstream
========
commit 23e0a63
Author: Anubhav Shelat <ashelat@redhat.com>
Date: Fri Jan 31 09:57:05 2025 -0500

description
===========
Currently, running "perf script flamegraph -a -F 99 sleep 1" should
produce flamegraph.html containing the flamegraph. Howevever, it gives a
segmentation fault.

This is caused because the flamegraph.py script is
supposed to take as input the output of "perf record", which should be
in stdin. This would require passing "-i -" to flamegraph.py. However,
the "flamegraph-report" script causes "perf script" command to take the
"-i -" option instead of flamegraph.py, which causes no problem for
"perf script", but causes a seg fault since flamegraph.py has no input
file. To fix this I added the "-i -" option directly to the
flamegraph-report script to ensure flamegraph.py gets input from stdin.

    Signed-off-by: Anubhav Shelat <ashelat@redhat.com>
    Tested-by: Michael Petlan <mpetlan@redhat.com>
    Link: https://lore.kernel.org/r/20250131145704.3164542-2-ashelat@redhat.com
    Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Signed-off-by: Anubhav Shelat <ashelat@redhat.com>

Author: AnubhavS1

tools/perf/scripts/python/bin/flamegraph-report

@@ -1,3 +1,3 @@
 #!/bin/bash
 # description: create flame graphs
-perf script -s "$PERF_EXEC_PATH"/scripts/python/flamegraph.py -- "$@"
+perf script -s "$PERF_EXEC_PATH"/scripts/python/flamegraph.py -i - -- "$@"