perf machine: Introduce machine__find_kernel_symbol_by_name()

To be used in the 'vmlinux matches kallsyms' 'perf test'  entry.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-m56g1853lz2c6nhnqxibq4jd@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>