bug: secp256 syscalls missing

[greged93]

The secp256 syscalls need to be added to the SELECTOR_TO_SYSCALL static. Currently running a contract containing a call to a secp256 syscall throws with:

Syscall handler invocation error: The selector '31202166147520941793195011415201397765240582401125720' is not in the syscall handler's selector to syscall map

The above is trying to use the Secp256k1GetPointFromX syscall.