Joan Quinn, a Beverly Hills arts patron and supporter and former West Coast editor of Interview magazine, has been reappointed to a second four-year term on the California Arts Council. Democratic Assembly Speaker Willie Brown named Quinn, a Republican, to the 11-member Republican-dominated state agency. She will serve until Dec. 31, 1991. The reappointment came as no surprise to Sacramento observers, even though Quinn had denounced some council policies last year. She has particularly objected to the diminishing frequency and length of council meetings, always open for public testimony. Before 1986, the council usually held eight one-day meetings a year. In 1987--as it plans to do in 1988--it held seven meetings, two of them lumped together for a two-day session. Quinn nonetheless was happy about the reappointment, cheering, "Four years! Yea for me," when she heard the news.