[CodeCompletion] _compilerInitialized and _local are UserInaccessible

These declaration modifiers are not meant to be used from user source
code. Mark them 'UserInaccessible' so code completion don't show them.

rdar://92970201

Author: rintaro

include/swift/AST/Attr.def

@@ -268,6 +268,7 @@ SIMPLE_DECL_ATTR(objcMembers, ObjCMembers,
   34)
 CONTEXTUAL_SIMPLE_DECL_ATTR(_compilerInitialized, CompilerInitialized,
   OnVar |
+  UserInaccessible |
   ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
   35)
 CONTEXTUAL_SIMPLE_DECL_ATTR(__consuming, Consuming,
@@ -727,6 +728,7 @@ DECL_ATTR(_backDeploy, BackDeploy,
 
 CONTEXTUAL_SIMPLE_DECL_ATTR(_local, KnownToBeLocal,
   DeclModifier | OnFunc | OnParam | OnVar |
+  UserInaccessible |
   ABIBreakingToAdd | ABIBreakingToRemove |
   APIBreakingToAdd | APIBreakingToRemove,
   130)

test/SourceKit/CodeComplete/complete_override.swift.response

@@ -1,15 +1,5 @@
 {
   key.results: [
-    {
-      key.kind: source.lang.swift.keyword,
-      key.name: "_compilerInitialized",
-      key.sourcetext: "_compilerInitialized",
-      key.description: "_compilerInitialized",
-      key.typename: "",
-      key.context: source.codecompletion.context.none,
-      key.typerelation: source.codecompletion.typerelation.notapplicable,
-      key.num_bytes_to_erase: 0
-    },
     {
       key.kind: source.lang.swift.keyword,
       key.name: "_const",
@@ -20,16 +10,6 @@
       key.typerelation: source.codecompletion.typerelation.notapplicable,
       key.num_bytes_to_erase: 0
     },
-    {
-      key.kind: source.lang.swift.keyword,
-      key.name: "_local",
-      key.sourcetext: "_local",
-      key.description: "_local",
-      key.typename: "",
-      key.context: source.codecompletion.context.none,
-      key.typerelation: source.codecompletion.typerelation.notapplicable,
-      key.num_bytes_to_erase: 0
-    },
     {
       key.kind: source.lang.swift.keyword,
       key.name: "actor",