[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/bits.go

@@ -0,0 +1,58 @@
+// Copyright 2023 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !amd64 || nosimd
+
+package swiss
+
+import (
+	"math/bits"
+	"unsafe"
+)
+
+const (
+	groupSize       = 8
+	maxAvgGroupLoad = 7
+
+	loBits uint64 = 0x0101010101010101
+	hiBits uint64 = 0x8080808080808080
+)
+
+type bitset uint64
+
+func metaMatchH2(m *metadata, h h2) bitset {
+	// https://graphics.stanford.edu/~seander/bithacks.html##ValueInWord
+	return hasZeroByte(castUint64(m) ^ (loBits * uint64(h)))
+}
+
+func metaMatchEmpty(m *metadata) bitset {
+	return hasZeroByte(castUint64(m) ^ hiBits)
+}
+
+func nextMatch(b *bitset) uint32 {
+	s := uint32(bits.TrailingZeros64(uint64(*b)))
+	*b &= ^(1 << s) // clear bit |s|
+	return s >> 3   // div by 8
+}
+
+func hasZeroByte(x uint64) bitset {
+	return bitset(((x - loBits) & ^(x)) & hiBits)
+}
+
+func castUint64(m *metadata) uint64 {
+	return *(*uint64)((unsafe.Pointer)(m))
+}
+
+//go:linkname fastrand runtime.fastrand
+func fastrand() uint32