fix: add runtime.rand and runtime.memhash for hash/maphash support

- Register hash/maphash in hasAltPkg map in runtime/build.go
- Add rand() function that bridges to fastrand64() in runtime overlay
- Add memhash() function that bridges to internal memhash() in runtime overlay
- Fixes issue where hash/maphash package failed with undefined symbols

Fixes #1338

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Co-authored-by: luoliwoshang <luoliwoshang@users.noreply.github.com>
Co-authored-by: xgopilot <noreply@goplus.org>

runtime/build.go

@@ -24,6 +24,7 @@ var hasAltPkg = map[string]none{
 	"crypto/subtle":            {},
 	"go/parser":                {},
 	"hash/crc32":               {},
+	"hash/maphash":             {},
 	"internal/abi":             {},
 	"internal/bytealg":         {},
 	"internal/chacha8rand":     {},