perf annotate: Move pcnt_with() to the annotation library

perf annotate: Move pcnt_with() to the annotation library

Out of the TUI code, since now all it touches is what is in 'struct
annotation'.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-kh5bbbgd7l4agv9oc5hnw0ui@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>