go mod: add indirect version of shirou/gopsutil to fix freebsd build

[amyangfei]

What problem does this PR solve?

Fix build failure in darwin/freebsd, related to shirou/gopsutil#853, shirou/gopsutil#958. master branch is ok

[2021-01-30T03:02:49.692Z] + make build
[2021-01-30T03:02:49.692Z] CGO_ENABLED=0 GO111MODULE=on go build  -trimpath  -ldflags '-X "github.com/pingcap/ticdc/pkg/version.ReleaseVersion=v4.0.11" -X "github.com/pingcap/ticdc/pkg/version.BuildTS=2021-01-30 03:02:49" -X "github.com/pingcap/ticdc/pkg/version.GitHash=f9ecdb2b448419d0770b44c579ef96c9d58bcac7" -X "github.com/pingcap/ticdc/pkg/version.GitBranch=heads/refs/tags/v4.0.11" -X "github.com/pingcap/ticdc/pkg/version.GoVersion=go version go1.13.4 darwin/amd64"' -o bin/cdc ./main.go
[2021-01-30T03:03:46.787Z] # github.com/shirou/gopsutil/disk
[2021-01-30T03:03:46.787Z] /Users/pingcap/gopkg/pkg/mod/github.com/shirou/gopsutil@v2.20.3+incompatible/disk/disk_darwin.go:67:51: cannot use stat.Mntfromname[:] (type []byte) as type []int8 in argument to common.IntToString
[2021-01-30T03:03:46.787Z] /Users/pingcap/gopkg/pkg/mod/github.com/shirou/gopsutil@v2.20.3+incompatible/disk/disk_darwin.go:68:49: cannot use stat.Mntonname[:] (type []byte) as type []int8 in argument to common.IntToString
[2021-01-30T03:03:46.787Z] /Users/pingcap/gopkg/pkg/mod/github.com/shirou/gopsutil@v2.20.3+incompatible/disk/disk_darwin.go:69:50: cannot use stat.Fstypename[:] (type []byte) as type []int8 in argument to common.IntToString
[2021-01-30T03:03:46.787Z] /Users/pingcap/gopkg/pkg/mod/github.com/shirou/gopsutil@v2.20.3+incompatible/disk/disk_darwin.go:85:43: cannot use stat.Fstypename[:] (type []byte) as type []int8 in argument to common.IntToString
[2021-01-30T03:03:46.787Z] make: *** [cdc] Error 2
script returned exit code 2

What is changed and how it works?

github.com/shirou/gopsutil is used in github.com/pingcap/sysutil, since 3.x and 2.x of gopsutil are not compatible, this is a workaround for ticdc build.

The root cause is github.com/shirou/gopsutil must be compatible with golang.org/x/sys

It is better to upgrade github.com/shirou/gopsutil in github.com/pingcap/sysutil, and the dependency in pd/tidb will be updated cascade

Check List

Tests

• Unit test
• Integration test

Release note

• No release note

[amyangfei]

/run-all-tests

[codecov-io]

Codecov Report

Merging #1385 (f9ecdb2) into release-4.0 (f9ecdb2) will not change coverage.
The diff coverage is n/a.

@@              Coverage Diff               @@
##           release-4.0      #1385   +/-   ##
==============================================
  Coverage      48.5304%   48.5304%           
==============================================
  Files              130        130           
  Lines            13235      13235           
==============================================
  Hits              6423       6423           
  Misses            6134       6134           
  Partials           678        678           

[zier-one]

/lgtm

[zier-one]

/merge

[ti-srebot]

/run-all-tests