This is as clear as mud - absent a SCOTUS ruling. A child born in the US is a citizen at birth [14th Amendment], but if his parents are citizens of another country [specifically, the father] AND that country asserts natural born status on the child, the child MAY or MAY NOT be a natural born citizen of the US.
Taking into account the probable definition that the Founding Fathers would have used - the child WOULD NOT be NBC, but that HAS NOT been decided by SCOTUS ...
Since when do other countries get to decide which of our citizens is eligible?
Granted, Zero doubtless thinks we ought to respect their opinions in that matter and others. But he's our first anti-American president, so that's hardly a surprise.