Bump all vendoring (#1612)

Update all vendoring to current releases.

Signed-off-by: Ben Kochie <superq@gmail.com>

vendor/honnef.co/go/tools/functions/pure.go

@@ -0,0 +1,46 @@
+package functions
+
+import (
+	"honnef.co/go/tools/ssa"
+)
+
+func filterDebug(instr []ssa.Instruction) []ssa.Instruction {
+	var out []ssa.Instruction
+	for _, ins := range instr {
+		if _, ok := ins.(*ssa.DebugRef); !ok {
+			out = append(out, ins)
+		}
+	}
+	return out
+}
+
+// IsStub reports whether a function is a stub. A function is
+// considered a stub if it has no instructions or exactly one
+// instruction, which must be either returning only constant values or
+// a panic.
+func IsStub(fn *ssa.Function) bool {
+	if len(fn.Blocks) == 0 {
+		return true
+	}
+	if len(fn.Blocks) > 1 {
+		return false
+	}
+	instrs := filterDebug(fn.Blocks[0].Instrs)
+	if len(instrs) != 1 {
+		return false
+	}
+
+	switch instrs[0].(type) {
+	case *ssa.Return:
+		// Since this is the only instruction, the return value must
+		// be a constant. We consider all constants as stubs, not just
+		// the zero value. This does not, unfortunately, cover zero
+		// initialised structs, as these cause additional
+		// instructions.
+		return true
+	case *ssa.Panic:
+		return true
+	default:
+		return false
+	}
+}