Use correct OpenSSL thread safety macros on OS X (closes #209) Create an Autoconf test to determine if pthread_t is a pointer or scalar type, and use the appropriate CRYPTO_THREADID_set macro based on the result.

fun f (x : int * float) : string = x
fun g (x : int * float * bool) : string = x
fun h (x : {A : int, B : float, C : bool}) : string = x