Ted Cruz was born to an American mother in Calgary, Alberta. He was an American citizen at birth and never had to go through the naturalization process. The "natural born citizen" requirement was established in Article II of the constitution, and is a term that refers to all people who gain the right of citizenship by birth, either by being born to American parents, or by being born on American soil. It does not refer exclusively to people who gained citizenship through jus soli, which was not even explicitly established in America until roughly 80 years after the original drafting of the Constitution.
I dislike Ted Cruz as much as the next liberal, but when you call him "Calgary Cruz" or imply that he isn't eligible to run for President, you don't come off as clever, you come off as ignorant of the law and a little bit nativist. Please stop.
Edit: So a bunch of people are asking for sources for my assertion. I thought it was fairly self evident, but the Congressional Research Service looked into it in 2011 and decided I was right:
The weight of legal and historical authority indicates that the term “natural born” citizen would mean a person who is entitled to U.S. citizenship “by birth” or “at birth,” either by being born “in” the United States and under its jurisdiction, even those born to alien parents; by being born abroad to U.S. citizen-parents; or by being born in other situations meeting legal requirements for U.S. citizenship “at birth.”