[AST] Promote getLifetimeAnnotation.

Move it up to Decl in preparation for getting it from AbstractFuncDecls.

Author: nate-chandler

include/swift/AST/Decl.h

@@ -986,6 +986,15 @@ class alignas(1 << DeclAlignInBits) Decl : public ASTAllocated<Decl> {
   /// Check if this is a declaration defined at the top level of the Swift module
   bool isStdlibDecl() const;
 
+  LifetimeAnnotation getLifetimeAnnotation() const {
+    auto &attrs = getAttrs();
+    if (attrs.hasAttribute<EagerMoveAttr>())
+      return LifetimeAnnotation::EagerMove;
+    if (attrs.hasAttribute<LexicalAttr>())
+      return LifetimeAnnotation::Lexical;
+    return LifetimeAnnotation::None;
+  }
+
   bool isNoImplicitCopy() const {
     return getAttrs().hasAttribute<NoImplicitCopyAttr>();
   }
@@ -2718,15 +2727,6 @@ class ValueDecl : public Decl {
   /// 'func foo(Int) -> () -> Self?'.
   GenericParameterReferenceInfo findExistentialSelfReferences(
       Type baseTy, bool treatNonResultCovariantSelfAsInvariant) const;
-
-  LifetimeAnnotation getLifetimeAnnotation() const {
-    auto &attrs = getAttrs();
-    if (attrs.hasAttribute<EagerMoveAttr>())
-      return LifetimeAnnotation::EagerMove;
-    if (attrs.hasAttribute<LexicalAttr>())
-      return LifetimeAnnotation::Lexical;
-    return LifetimeAnnotation::None;
-  }
 };
 
 /// This is a common base class for declarations which declare a type.