Temporarily mark ArraysObjc test unsupported for watchsimulator-i386.

Earlier, I accidentally marked Arrays.swift.gyb, however the test that
is failing is ArraysObjc.swift.gyb.

(cherry picked from commit c53d0eb)

Author: varungandhi-apple

validation-test/stdlib/ArraysObjc.swift.gyb

@@ -9,7 +9,8 @@
 // REQUIRES: objc_interop
 
 // FIXME: rdar://problem/55944126
-// UNSUPPORTED: CPU=armv7s || CPU=armv7k
+// FIXME: rdar://problem/79626782 (test fails for watchsimulator-i386)
+// UNSUPPORTED: CPU=armv7s || CPU=armv7k || CPU=i386
 
 import Darwin
 import Foundation