perf tools: Enable warnings when compiling BPF programs

perf tools: Enable warnings when compiling BPF programs

Add -Wall -Werror when compiling BPF skeletons.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20210306080840.3785816-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>