value-prof: Fix abs uses in value-prof.c [PR93962]

value-prof: Fix abs uses in value-prof.c [PR93962]

Jeff has recently fixed dump_histogram_value to use std::abs instead of abs,
because on FreeBSD apparently the ::abs isn't overloaded and only has
int abs (int);
Seems on Solaris /usr/include/iso/stdlib_iso.h abs has:
int abs (int);
long abs (long);
overloads but already not
long long abs (long long);
and there is another abs use in get_nth_most_common_value, also on int64_t.
The long long std::abs (long long); overload is there only in C++11 and we
in GCC10 still support C++98.

Martin has said that a counter should never be INT64_MIN, so IMHO it is
better to use abs_hwi which will assert that.

2020-03-11  Jakub Jelinek  <jakub@redhat.com>

	PR bootstrap/93962
	* value-prof.c (dump_histogram_value): Use abs_hwi instead of
	std::abs.
	(get_nth_most_common_value): Use abs_hwi instead of abs.