Remove unnecessary use of LLVM_LVALUE_FUNCTION

We're already using lvalue functions elsewhere in the codebase, so this
isn't adding value. In the "next" branch, this macro has been removed,
so this fixes a build error in that case.

Author: benlangmuir

include/swift/Syntax/AbsoluteRawSyntax.h

@@ -397,11 +397,11 @@ class OptionalStorage<AbsoluteRawSyntax> {
 
   bool hasValue() const { return !Storage.isNull(); }
 
-  AbsoluteRawSyntax &getValue() LLVM_LVALUE_FUNCTION {
+  AbsoluteRawSyntax &getValue() & {
     assert(hasValue());
     return Storage;
   }
-  AbsoluteRawSyntax const &getValue() const LLVM_LVALUE_FUNCTION {
+  AbsoluteRawSyntax const &getValue() const & {
     assert(hasValue());
     return Storage;
   }

include/swift/Syntax/SyntaxData.h

@@ -416,11 +416,11 @@ class OptionalStorage<SyntaxDataRef> {
 
   bool hasValue() const { return !Storage.getAbsoluteRaw().isNull(); }
 
-  SyntaxDataRef &getValue() LLVM_LVALUE_FUNCTION {
+  SyntaxDataRef &getValue() & {
     assert(hasValue());
     return Storage;
   }
-  SyntaxDataRef const &getValue() const LLVM_LVALUE_FUNCTION {
+  SyntaxDataRef const &getValue() const & {
     assert(hasValue());
     return Storage;
   }