perf script flamegraph: Avoid d3-flame-graph package dependency

Currently flame graph generation requires a d3-flame-graph template to
be installed. Unfortunately this is hard to come by for things like
Debian [1].

If the template isn't installed then ask if it should be downloaded from
jsdelivr CDN. The downloaded HTML file is validated against an md5sum.
If the download fails, generate a minimal flame graph with the
javascript coming from links to jsdelivr CDN.

v3. Adds a warning message and quits before download in live mode.
v2. Change the warning to a prompt about downloading and add the
    --allow-download command line flag. Add an md5sum check for the
    downloaded HTML.

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=996839

Reviewed-by: Andreas Gerstmayr <[email protected]>
Signed-off-by: Ian Rogers <[email protected]>
Cc: [email protected]
Cc: Alexander Shishkin <[email protected]>
Cc: Brendan Gregg <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Martin Spier <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: https://lore.kernel.org/r/[email protected] # v3 discussion
Link: https://lore.kernel.org/r/[email protected] # v2 discussion
Link: https://lore.kernel.org/r/CAP-5=fXi_9zdhTAoYApiFQoLURAvpEatFzU3uL23o3zs=z25ZQ@mail.gmail.com # v1 discussion
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions