fmt: clear width and precision in fmt.init

[nkzxw]

width and precision may be abnormally large when missing args.
it case unnecessary large mem alloc, as follows:

func test() {
var m runtime.MemStats
runtime.ReadMemStats(&m)
fmt.Printf("1. mem init: %+v\n", m.TotalAlloc)
fmt.Printf("2. fault print: %.9000000f\n", "aaa")
fmt.Printf("3. normal print %02d%02d\n", 1, 1)
runtime.ReadMemStats(&m)
fmt.Printf("4. mem after: %+v\n", m.TotalAlloc)
}
// 1. mem init: 105856
// 2. fault print: %!f(string=aaa)
// 3. normal print 0101
// 4. mem after: 18123680

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[gopherbot]

This PR (HEAD: 83aa3b1) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/go/+/495156 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

Message from Gopher Robot:

Patch Set 1:

Congratulations on opening your first change. Thank you for your contribution!

Next steps:
A maintainer will review your change and provide feedback. See
https://go.dev/doc/contribute#review for more info and tips to get your
patch through code review.

Most changes in the Go project go through a few rounds of revision. This can be
surprising to people new to the project. The careful, iterative review process
is our way of helping mentor contributors and ensuring that their contributions
have a lasting impact.

During May-July and Nov-Jan the Go project is in a code freeze, during which
little code gets reviewed or merged. If a reviewer responds with a comment like
R=go1.11 or adds a tag like "wait-release", it means that this CL will be
reviewed as part of the next development cycle. See https://go.dev/s/release
for more details.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 1: Run-TryBot+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gopher Robot:

Patch Set 1: TryBot-Result-1

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 2: Run-TryBot+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gopher Robot:

Patch Set 2:

(2 comments)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gopher Robot:

Patch Set 2: TryBot-Result+1

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 2: Code-Review+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Rob Pike:

Patch Set 2:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Rob Pike:

Patch Set 2:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/495156.
After addressing review feedback, remember to publish your drafts!