stdlib: add migration aids for SetAlgebra API

rdar://problem/26227732

Author: gribozavr

stdlib/public/core/SetAlgebra.swift

@@ -549,3 +549,60 @@ extension SetAlgebra {
 @available(*, unavailable, renamed: "SetAlgebra")
 public typealias SetAlgebraType = SetAlgebra
 
+extension SetAlgebra {
+  @available(*, unavailable, renamed: "intersection")
+  public func intersect(_ other: Self) -> Self {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "symmetricDifference")
+  public func exclusiveOr(_ other: Self) -> Self {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "formUnion")
+  public mutating func unionInPlace(_ other: Self) {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "formIntersection")
+  public mutating func intersectInPlace(_ other: Self) {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "formSymmetricDifference")
+  public mutating func exclusiveOrInPlace(_ other: Self) {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "isSubset(of:)")
+  public func isSubsetOf(_ other: Self) -> Bool {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "isDisjoint(with:)")
+  public func isDisjointWith(_ other: Self) -> Bool {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "isSuperset(of:)")
+  public func isSupersetOf(_ other: Self) -> Bool {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "subtract")
+  public mutating func subtractInPlace(_ other: Self) {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "isStrictSuperset(of:)")
+  public func isStrictSupersetOf(_ other: Self) -> Bool {
+    Builtin.unreachable()
+  }
+
+  @available(*, unavailable, renamed: "isStrictSubset(of:)")
+  public func isStrictSubsetOf(_ other: Self) -> Bool {
+    Builtin.unreachable()
+  }
+}
+