perf callchain: Refactor callchain option parsing

perf callchain: Refactor callchain option parsing

record_opts__parse_callchain is shared by builtin-record and
builtin-trace, it is declared in callchain.h. Move the declaration to
callchain.c for consistency with the header. In other cases make the
option callback a small static stub that then calls into callchain.c.

Make the no argument '-g' callchain option just a short-cut for
'--call-graph fp' so that there is consistency in how the arguments
are handled. This requires the const char* string to be strdup-ed in
__parse_callchain_report_opt. For consistency also make
parse_callchain_record use strdup and remove some unnecessary
casts. Also, be more explicit about the '-g' behavior if there is a
.perfconfig file setting.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>