x/tools/cmd/signature-fuzzer: test failures when module's language version is 1.24

[dmitshur]

When x/tools' go.mod is updated to Go language 1.24 or newer (which will happen this August based on https://go.dev/s/release#timeline and https://go.dev/design/69095-x-repo-continuous-go#why-1_n_1_0), there are some tests in cmd/signature-fuzzer that will begin to fail:

tools $ go test -count=1 ./cmd/signature-fuzzer/internal/fuzz-generator 
ok  	golang.org/x/tools/cmd/signature-fuzzer/internal/fuzz-generator	6.828s
tools $ go mod edit -go=1.24
tools $ go test -count=1 ./cmd/signature-fuzzer/internal/fuzz-generator
wraprand consistency check failed:
 checker: {f32:3 f64:12 i:76}
 caller: {f32:3 f64:12 i:77}
--- FAIL: TestIsBuildable (0.13s)
panic: bad [recovered]
	panic: bad
[…]
tools $ go mod edit -go=1.22.0                                         
tools $ go test -count=1 ./cmd/signature-fuzzer/internal/fuzz-generator
ok  	golang.org/x/tools/cmd/signature-fuzzer/internal/fuzz-generator	7.012s
[...]

This is being reported early thanks to a -tiplang builder (see https://ci.chromium.org/ui/p/golang/builders/ci/x_tools-gotip-linux-amd64-tiplang). It's not necessarily a problem today since x/tools/go.mod's go directive is at 1.22.0, but does need to be investigated and fixed at some point, and this is the tracking issue for that.

CC @golang/tools-team.

[gopherbot]

Change https://go.dev/cl/647896 mentions this issue: cmd/signature-fuzzer/internal/fuzz-generator: update to math/rand/v2

[gopherbot]

Change https://go.dev/cl/648676 mentions this issue: main.star: remove known issues for -tiplang builder in x/crypto, x/tools