Go 1.17.2 fixes some miscompilation issues on amd64 and a runtime issue with timers.
While the upgrade is not strictly necessary for go-ethereum right now, it is still good
to be up-to-date.

Support for this Ubuntu release has ended on July 22 2021 and
Launchpad no longer accepts uploads for it.

The new linter version is built with go 1.17 and thus includes the go vet
check for mismatched +build and go:build lines.

Fortunately, no new warnings are reported with this update.

With the update to a newer AppVeyor build image, creating the Windows
installer no longer worked because of a string quoting error in EnvVarUpdate.nsh.

This applies the fix recommended in https://stackoverflow.com/questions/62081765.

This fixes a regression introduced in #22804.

This PR cleans up the CI build system and fixes a couple of issues.

- The go tool launcher code has been moved to internal/build. With the new
  toolchain functions, the environment of the host Go (i.e. the one that built
  ci.go) and the target Go (i.e. the toolchain downloaded by -dlgo) are isolated
  more strictly. This is important to make cross compilation and -dlgo work
  correctly in more cases.
- The -dlgo option now skips the download and uses the host Go if the running Go
  version matches dlgoVersion exactly.
- The 'test' command now supports -dlgo, -cc and -arch. Running unit tests with
  foreign GOARCH is occasionally useful. For example, it can be used to run
  32-bit tests on Windows. It can also be used to run darwin/amd64 tests on
  darwin/arm64 using Rosetta 2.
- The 'aar', 'xcode' and 'xgo' commands now use a slightly different method to
  install external tools. They previously used `go get`, but this comes with the
  annoying side effect of modifying go.mod. They now use `go install` instead,
  which is the recommended way of installing tools without modifying the local
  module.
- The old build warning about outdated Go version has been removed because we're
  much better at keeping backwards compatibility now.

* build: upgrade to golangci-lint v1.39.0

* consensus/ethash: fix go vet warning regarding reflect.SliceHeader

* eth/catalyst: fix lint issue

* consensus/ethash: fix bug in memoryMapFile

This fixes some issues in crypto/signify and makes release signing work.

The archive signing step in ci.go used getenvBase64, which decodes the key data.
This is incorrect here because crypto/signify already base64-decodes the key.

* internal/build: implement signify's signing func
* Add signify to the ci utility
* fix output file format
* Add unit test for signify
* holiman's + travis' feedback
* internal/build: verify signify's output
* crypto: move signify to common dir
* use go-minisign to verify binaries
* more holiman feedback
* crypto, ci: support minisign output
* only accept one-line trusted comments
* configurable untrusted comments
* code cleanup in tests
* revert to use ed25519 from the stdlib
* bug: fix for empty untrusted comments
* write timestamp as comment if trusted comment isn't present
* rename line checker to commentHasManyLines
* crypto: added signify fuzzer (#6)
* crypto: added signify fuzzer
* stuff
* crypto: updated signify fuzzer to fuzz comments
* crypto: repro signify crashes
* rebased fuzzer on build-signify branch
* hide fuzzer behind gofuzz build flag
* extract key data inside a single function
* don't treat \r as a newline
* travis: fix signing command line
* do not use an external binary in tests
* crypto: move signify to crypto/signify
* travis: fix formatting issue
* ci: fix linter build after package move

Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>

This fixes cross-build and mobile framework failures.
It also disables the mac test builder because it was failing
all the time in hard to understand ways and we can't afford
it anymore under Travis CI's new pricing.

This new flag downloads a known version of Go and builds with it. This
is meant for environments where we can't easily upgrade the installed Go
version.

* .travis.yml: remove install step for PR test builders

We added this step originally to avoid re-building everything
for every test. go test has become much smarter in recent go
releases, so we no longer need to install anything here.

* ci: tooltips for javadoc for mobile app

* f space

* Disable symbol table and DWARF generation by default.
Trimpath if compiling with Go >= 1.13

* Set Go to minimum version 1.13. Revert debug symbol changes.

* build: upgrade to golangci-lint v1.27.0

* build: raise lint timeout to 3 minutes

* build: Fix CLI params for windows LNK files

closes #21054

* Remove parameters

* travis, appveyor, build, Dockerfile: bump Go to 1.14.2

* travis, appveyor: force GO111MODULE=on for every build

* accounts/scwallet: remove unnecessary uses of fmt.Sprintf

* cmd/puppeth: remove unnecessary uses of fmt.Sprintf

* p2p/discv5: remove unnecessary use of fmt.Sprintf

* whisper/mailserver: remove unnecessary uses of fmt.Sprintf

* core: goimports -w tx_pool_test.go

* eth/downloader: goimports -w downloader_test.go

* build: upgrade to golangci-lint 1.24.0

* build: upgrade golangci to 1.22.2

* .golangci.yml: don't fail on asset deadcode