Disables LLVM PR8927 check

otherwise it won't compile for iOS
#define JS_NO_JSVAL_JSID_STRUCT_TYPES

This is needed ir oder to compile release and debug builds
better xcode directory lookup

uses `xcode-select -p` instead of hardcoded path
Uses the IOS_SDK 7.0

Uses the IOS_SDK 7.0
regenerated configure