[ios] fix cycle in EXAnalytics and EXEnvironment
[ios] fix cycle in EXAnalytics and EXEnvironment

exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent