build: add support of Darwin arm64 (Apple Silicon chipset) for native mode and cross-compile

[DeckerSU]

This PR enables users to build KomodoOcean for the arm64-apple-darwin triplet (Darwin aarch64). The build is supported for both cross-compilation and native compilation for Apple Silicon chips. It was tested with the following environment:

sw_vers && pkgutil --pkg-info=com.apple.pkg.CLTools_Executables && clang --version
...
ProductName:		macOS
ProductVersion:		15.1
BuildVersion:		24B83
package-id: com.apple.pkg.CLTools_Executables
version: 16.1.0.0.1.1729049160
volume: /
location: /
install-time: 1731199973
Apple clang version 16.0.0 (clang-1600.0.26.4)
Target: arm64-apple-darwin24.1.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

If you’ve just upgraded from an earlier OS version to macOS Sequoia, you may need to reinstall XCode Command Line Tools as described here.

Also, note that if you are building natively for arm64 macOS, the build script will prompt you to upgrade Berkeley DB to 6.2.32. This version is still under testing, so proceed at your own risk. Be sure to back up your wallet.dat file before using the daemon or wallet with the updated BDB version.

The zcutil directory now includes the following additional build scripts:

• build-mac.sh - Native build for macOS x86_64. (If building on Apple Silicon, use arch -x86_64 zsh before starting the build to switch architecture / use Rosetta). Use this when building directly on a Mac.
• build-mac-cross.sh - Cross-compile on Linux for macOS x86_64. This will produce Mach-O 64-bit x86_64 executable binaries.
• build-mac-arm.sh - Native build for macOS aarch64. Use this on an Apple Silicon Mac to perform a native build and obtain Mach-O 64-bit executable arm64 binaries.
• build-mac-arm-cross.sh - Cross-compile from Linux for macOS aarch64.
• build-aarch64-cross.sh - Cross-compile for generic aarch64 targets.

These scripts help streamline the build process across different architectures and operating environments.