perf bpf: Move the declaration of struct rq

perf bpf: Move the declaration of struct rq

struct rq is defined in vmlinux.h when the vmlinux.h is generated,
this causes a redefinition failure if it is declared in
lock_contention.bpf.c. Move the definition to vmlinux.h for
consistency with the generated version.

Fixes: 760ebc45746b ("perf lock contention: Add empty 'struct rq' to satisfy libbpf 'runqueue' type verification")
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: James Clark <james.clark@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230623041405.4039475-3-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>