perf record: Ensure return non-zero rc when mmap fail

perf record: Ensure return non-zero rc when mmap fail

perf_evlist__mmap_ex() can fail without setting errno (for example, fail
in condition checking. In this case all syscall is success).

If this happen, record__open() incorrectly returns 0. Force setting rc
is a quick way to avoid this problem, or we have to follow all possible
code path in perf_evlist__mmap_ex() to make sure there's at least one
system call before returning an error.

Signed-off-by: Wang Nan <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: He Kuang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Zefan Li <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: He Kuang <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>