perf memswap: Split the byteswap memory range wrappers from util.[ch]

perf memswap: Split the byteswap memory range wrappers from util.[ch]

Just one more step into splitting util.[ch] to reduce the includes hell.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.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-navarr9mijkgwgbzu464dwam@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>