all: format code according to Go 1.19 rules

Go 1.19 started reformatting code in a way that makes it more obvious
how it will be rendered on pkg.go.dev. It gets it almost right, but not
entirely. Therefore, I had to modify some of the comments so that they
are formatted correctly.

src/internal/task/task_stack_avr.go

@@ -29,6 +29,7 @@ type calleeSavedRegs struct {
 
 // archInit runs architecture-specific setup for the goroutine startup.
 // Note: adding //go:noinline to work around an AVR backend bug.
+//
 //go:noinline
 func (s *state) archInit(r *calleeSavedRegs, fn uintptr, args unsafe.Pointer) {
 	// Store the initial sp for the startTask function (implemented in assembly).