Merge branch 'bpf-bpftool-batch-improvements'

Merge branch 'bpf-bpftool-batch-improvements'

Quentin Monnet says:

====================
Several enhancements for bpftool batch mode are introduced in this series.

More specifically, input files for batch mode gain support for:
  * comments (starting with '#'),
  * continuation lines (after a line ending with '\'),
  * arguments enclosed between quotes.

Also, make bpftool able to read from standard input when "-" is provided as
input file name.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>