runtime: print more information on stack overflow

Print the current SP and (old) stack bounds when the stack grows
too large. This helps to identify the problem: whether a large
stack is used, or something else goes wrong.

For #35470.

Change-Id: I34a4064d5c7280978391d835e171b90d06f87222
Reviewed-on: https://go-review.googlesource.com/c/go/+/207351
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

src/runtime/stack.go

@@ -1030,6 +1030,7 @@ func newstack() {
 	newsize := oldsize * 2
 	if newsize > maxstacksize {
 		print("runtime: goroutine stack exceeds ", maxstacksize, "-byte limit\n")
+		print("runtime: sp=", hex(sp), " stack=[", hex(gp.stack.lo), ", ", hex(gp.stack.hi), "]\n")
 		throw("stack overflow")
 	}