[performance] update go-structr and go-mutexes with memory usage improvements (#2909)

* update go-structr and go-mutexes with memory usage improvements

* bump to go-structr v0.8.4

vendor/github.com/dolthub/swiss/README.md

@@ -0,0 +1,54 @@
+# SwissMap
+
+SwissMap is a hash table adapated from the "SwissTable" family of hash tables from [Abseil](https://abseil.io/blog/20180927-swisstables). It uses [AES](https://github.com/dolthub/maphash) instructions for fast-hashing and performs key lookups in parallel using [SSE](https://en.wikipedia.org/wiki/Streaming_SIMD_Extensions) instructions. Because of these optimizations, SwissMap is faster and more memory efficient than Golang's built-in `map`. If you'd like to learn more about its design and implementation, check out this [blog post](https://www.dolthub.com/blog/2023-03-28-swiss-map/) announcing its release.
+
+
+## Example
+
+SwissMap exposes the same interface as the built-in `map`. Give it a try using this [Go playground](https://go.dev/play/p/JPDC5WhYN7g).
+
+```go
+package main
+
+import "github.com/dolthub/swiss"
+
+func main() {
+	m := swiss.NewMap[string, int](42)
+
+	m.Put("foo", 1)
+	m.Put("bar", 2)
+
+	m.Iter(func(k string, v int) (stop bool) {
+		println("iter", k, v)
+		return false // continue
+	})
+
+	if x, ok := m.Get("foo"); ok {
+		println(x)
+	}
+	if m.Has("bar") {
+		x, _ := m.Get("bar")
+		println(x)
+	}
+
+	m.Put("foo", -1)
+	m.Delete("bar")
+
+	if x, ok := m.Get("foo"); ok {
+		println(x)
+	}
+	if m.Has("bar") {
+		x, _ := m.Get("bar")
+		println(x)
+	}
+
+	m.Clear()
+
+	// Output:
+	// iter foo 1
+	// iter bar 2
+	// 1
+	// 2
+	// -1
+}
+```