Multiple fixes:
- building on Apple Silicon Macs - remove the assumptions that the build machine is always x86_64
- fix badly broken build.sh for Mac, especially with getopts for options & params
- extend build-ios.sh to allow building for iOS-derived platforms like visionOS

The expected iOS build invocation is:
build-ios.sh [clean] [release|debug] ${ARCH} ${PLATFORM}
where
ARCH = arm64|arm64e|x86_64
PLATFORM = iphoneos|iphonesimulator|xros|xrsimulator

The verification pipeline uses older Xcode
-Wno-unused-but-set-variable is unknown to older compilers, add -Wno-unknown-warning-option