all: fix printf(var) mistakes newly found in golang.org/x repos

[dmitshur]

Some golang.org/x repos have new findings from issue #68796 being resolved.
This issue is to track fixing them all.

CC @adonovan.

[gopherbot]

Change https://go.dev/cl/610816 mentions this issue: all: fix printf(var) mistakes detected by latest printf checker

[dmitshur]

List of golang.org/x repos that need attention:

• x/build (fix in CL 610816)
• x/crypto (fix in CL 610797)
• x/net (fix in CL 610799)
• x/text (fix in CL 610676)
• x/benchmarks (fix in CL 610915)
• x/exp (fix in CL 610935)
• x/mobile (fix in CL 610800)
• x/pkgsite (fix in CL 610517)
• x/vulndb (fix in CL 610955)
• x/sys (fix in CL 610940)

[gopherbot]

Change https://go.dev/cl/610799 mentions this issue: websocket: fix printf(var) mistake detected by latest printf checker

[gopherbot]

Change https://go.dev/cl/610676 mentions this issue: all: fix printf(var) mistakes detected by latest printf checker

[gopherbot]

Change https://go.dev/cl/610915 mentions this issue: all: fix printf(var) mistakes detected by latest printf checker

[gopherbot]

Change https://go.dev/cl/610935 mentions this issue: rand: fix printf(var) mistake detected by latest printf checker

[gopherbot]

Change https://go.dev/cl/610800 mentions this issue: all: fix printf(var) mistakes detected by latest printf checker

[gopherbot]

Change https://go.dev/cl/610955 mentions this issue: all: fix printf(var) mistakes detected by latest printf checker