Compute layout when emitting an other-constructor reference.

Fixes SE-9233, a crash due to a failure to validate a storage
declaration within a protocol when generating a call to an
initiializer.

Author: rjmccall

lib/Sema/CSApply.cpp

@@ -1630,6 +1630,8 @@ namespace {
 
       auto ref = ConcreteDeclRef(ctor, substitutions);
 
+      tc.requestMemberLayout(ctor);
+
       // The constructor was opened with the allocating type, not the
       // initializer type. Map the former into the latter.
       auto resultTy = solution.simplifyType(openedFullType);

test/multifile/Inputs/protocol-extension-init-helper.swift

@@ -0,0 +1,4 @@
+protocol P {
+  init()
+  var x: Int { get set }
+}

test/multifile/protocol-extension-init.swift

@@ -0,0 +1,8 @@
+// RUN: %target-swift-frontend -emit-ir -module-name test %S/Inputs/protocol-extension-init-helper.swift -primary-file %s
+
+// SE-9233: compute layout when emitting an other-constructor reference
+extension P {
+  public init(possibly: Bool) {
+    self.init()
+  }
+}