cmd/gf: fix gen enums failed in go version v1.22.1

[oldme-git]

Dear reviewer:
因为 golang.org/x/tools 过低，和 Go 1.22.1 不兼容，导致 gf gen enums 失败。堆栈信息：

PS D:\project\gf\cmd\gf> go run .\main.go gen enums
scanning for enums: D:\project\gf\cmd\gf
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
        panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x153b8cf]

goroutine 490 [running]:
go/types.(*Checker).handleBailout(0xc000c42200, 0xc000047bd0)
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/check.go:367 +0x88
panic({0x19b2e40?, 0x28a30c0?})
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/runtime/panic.go:770 +0x132
go/types.(*StdSizes).Sizeof(0x0, {0x1c76118, 0x28adee0})
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/sizes.go:228 +0x30f
go/types.(*Config).sizeof(...)
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/sizes.go:333
go/types.representableConst.func1({0x1c76118?, 0x28adee0?})
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/const.go:76 +0x9e
go/types.representableConst({0x1c79eb8, 0x27a62c0}, 0xc000c42200, 0x28adee0, 0xc000045fe8)
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/const.go:92 +0x192
go/types.(*Checker).representation(0xc000c42200, 0xc00090d0c0, 0x28adee0)
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/const.go:256 +0x65
go/types.(*Checker).implicitTypeAndValue(0xc000c42200, 0xc00090d0c0, {0x1c76118, 0x28adee0})
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/expr.go:375 +0x2d7
go/types.(*Checker).convertUntyped(0xc000c42200, 0xc00090d0c0, {0x1c76118, 0x28adee0})
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/go/types/const.go:289 +0x3f
go/types.(*Checker).matchTypes(0xc000c42200, 0xc00090d080, 0xc00090d0c0)
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/sync/once.go:74 +0xc2
sync.(*Once).Do(...)
        C:/Users/half/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.22.2.windows-amd64/src/sync/once.go:65
golang.org/x/tools/go/packages.(*loader).loadRecursive(0x0?, 0x0?)
        C:/Users/half/go/pkg/mod/golang.org/x/tools@v0.7.0/go/packages/packages.go:839 +0x4a
golang.org/x/tools/go/packages.(*loader).loadRecursive.func1.1(0x0?)
        C:/Users/half/go/pkg/mod/golang.org/x/tools@v0.7.0/go/packages/packages.go:846 +0x26
created by golang.org/x/tools/go/packages.(*loader).loadRecursive.func1 in goroutine 482
        C:/Users/half/go/pkg/mod/golang.org/x/tools@v0.7.0/go/packages/packages.go:845 +0x94
exit status 2

Fixes #3564