Relative path include works in the regular build due to -I paths but may
fail in other situations.

v2. Rebase. Comments on v1 were that we should handle include paths
    differently and it is agreed that can be a sensible refactor but
    beyond the scope of this change.
https://lore.kernel.org/lkml/20210504191227.793712-1-irogers@google.com/Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20210923154254.737657-1-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>