perf tools fixes for v7.0: 2nd batch

o Fix parsing 'overwrite' in command line event definitions in
  big-endian machines by writing correct union member.

o Fix finding default metric in 'perf stat'.

o Fix relative paths for including headers in 'perf kvm stat'.

o Sync header copies with the kernel sources: msr-index.h, kvm,
  build_bug.h.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
--
2.53.0

tools headers: Synchronize linux/build_bug.h with the kernel sources

To pick up the changes in:

  6ffd853b0b10e1e2 ("build_bug.h: correct function parameters names in kernel-doc")

That just add some comments, addressing this perf tools build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/include/linux/build_bug.h include/linux/build_bug.h

Please take a look at tools/include/uapi/README for further info on this
synchronization process.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>