gofmt apply inconsistent whitespace around operator expressions

[kujohn]

What version of Go are you using (go version)?

$ go version
go version go1.16.3 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/abc/Library/Caches/go-build"
GOENV="/Users/abc/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/abc/go/pkg/mod"
GOOS="darwin"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.16.3/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.16.3/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.16.3"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/tb/p57hxlwn0l760vcrm2vx_xvc0000gn/T/go-build969478116=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Run gofmt on:

x := 2*4
log.Println("%v", 3*5)

What did you expect to see?

x := 2 * 4
log.Println("%v", 3 * 5)

What did you see instead?

x := 2 * 4
log.Println("%v", 3*5)

[mvdan]

dup of #34426.