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/reflect/type.go

@@ -404,7 +404,7 @@ const (
 
 // The base type struct. All type structs start with this.
 type rawType struct {
-	meta uint8 // metadata byte, contains kind and flags (see contants above)
+	meta uint8 // metadata byte, contains kind and flags (see constants above)
 }
 
 // All types that have an element type: named, chan, slice, array, map (but not

src/reflect/value_test.go

@@ -164,7 +164,7 @@ func TestTinyMap(t *testing.T) {
 	// make sure we can get it out
 	v2 := refut.MapIndex(ValueOf(unmarshalerText{"x", "y"}))
 	if !v2.IsValid() || !v2.Bool() {
-		t.Errorf("Failed to look up map struct key with refection")
+		t.Errorf("Failed to look up map struct key with reflection")
 	}
 
 	// put in a key with reflection