tools include: Add UINT_MAX def to kernel.h

The kernel has it and some files we got from there would require us
including the userland header for that, so add it conditionally.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-gmwyal7c9vzzttlyk6u59rzn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>