GNUmakefile: add spellfix target, use it. (#4387)

TODO: Remove the go.mod/go.sum in internal/tools once doing so doesn't break CI (e.g. once we drop support for go 1.19)

* builder/cc1as.h: fix typo found by 'make spell'
* GNUmakefile: remove exception for inbetween, fix instance now found by 'make spell'
* GNUmakefile: remove exception for programmmer, fix instance now found by 'make spell'
* go.mod: use updated misspell. GNUmakefile: add spellfix target, use it.
* ignore directories properly when invoking spellchecker.
* make spell: give internal/tools its own go.mod, as misspell requires newer go
* make lint: depend on tools and run the installed revive
(which was perhaps implied by the change that added revive to internal/tools,
but not required in GNUmakefile until we gave internal/tools its own temporary go.mod)
* .github: now that 'make spell' works well, run it from CI
* GNUmakefile: make spell now aborts if it finds misspelt words, so what it finds doesn't get lost in CI logs
* GNUmakefile: tools: avoid -C option on go generate to make test-llvm15-go119 circleci job happy, see
https://cs.opensource.google/go/go/+/2af48cbb7d85e5fdc635e75b99f949010c607786
* internal/tools/go.mod: fix format of go version to leave out patchlevel, else go complains.

src/crypto/rand/rand_arc4random.go

@@ -3,7 +3,7 @@
 // This implementation of crypto/rand uses the arc4random_buf function
 // (available on both MacOS and WASI) to generate random numbers.
 //
-// Note: arc4random_buf (unlike what the name suggets) does not use the insecure
+// Note: arc4random_buf (unlike what the name suggests) does not use the insecure
 // RC4 cipher. Instead, it uses a high-quality cipher, varying by the libc
 // implementation.
 

src/crypto/tls/tls.go

@@ -101,7 +101,7 @@ type Dialer struct {
 //
 // The returned Conn, if any, will always be of type *Conn.
 func (d *Dialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
-	return nil, errors.New("tls:DialContext not implmented")
+	return nil, errors.New("tls:DialContext not implemented")
 }
 
 // LoadX509KeyPair reads and parses a public/private key pair from a pair