iosx8664: Set min iOS version to 9.0 to enable TLS
iosx8664: Set min iOS version to 9.0 to enable TLS

With Xcode 8.3, __thread worked with iOS x86-64 (simulator) builds when
passing -miphoneos-version-min=8.0 to the compiler, but Xcode 12.2 seems
to require -miphoneos-version-min=9.0 to enable __thread with such
builds.

libjpeg-turbo/buildscripts