Joe Brondo, author and co-star of “Bluebirds,” which will open a six-performance engagement at Guild Hall on Friday, Feb. 20, did not grow up dreaming of a life in the theater. An East Hampton native, he was obsessed with computers while in high school. “That was all I did, I was always hunched over my desk,” he recalled. “I was kind of a class clown, but on the weirder end of the spectrum. I wasn’t the super-popular goofball.”