[NFC] Refactoring PropertyAttributeKind for ObjCPropertyDecl and ObjCDeclSpec.

This is a code clean up of the PropertyAttributeKind and
ObjCPropertyAttributeKind enums in ObjCPropertyDecl and ObjCDeclSpec that are
exactly identical. This non-functional change consolidates these enums
into one. The changes are to many files across clang (and comments in LLVM) so
that everything refers to the new consolidated enum in DeclObjCCommon.h.

2nd Landing Attempt...

Differential Revision: https://reviews.llvm.org/D77233
diff --git a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
index e0e3420..c46ba98 100644
--- a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
+++ b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
@@ -941,9 +941,10 @@
 
   unsigned Attributes = PD->getPropertyAttributes();
   if (mustSynthesizeSetterGetterMethod(IMD, PD, true /*getter*/)) {
-    bool GenGetProperty = !(Attributes & ObjCPropertyDecl::OBJC_PR_nonatomic) &&
-                          (Attributes & (ObjCPropertyDecl::OBJC_PR_retain |
-                                         ObjCPropertyDecl::OBJC_PR_copy));
+    bool GenGetProperty =
+        !(Attributes & ObjCPropertyAttribute::kind_nonatomic) &&
+        (Attributes & (ObjCPropertyAttribute::kind_retain |
+                       ObjCPropertyAttribute::kind_copy));
     std::string Getr;
     if (GenGetProperty && !objcGetPropertyDefined) {
       objcGetPropertyDefined = true;
@@ -1002,8 +1003,8 @@
 
   // Generate the 'setter' function.
   std::string Setr;
-  bool GenSetProperty = Attributes & (ObjCPropertyDecl::OBJC_PR_retain |
-                                      ObjCPropertyDecl::OBJC_PR_copy);
+  bool GenSetProperty = Attributes & (ObjCPropertyAttribute::kind_retain |
+                                      ObjCPropertyAttribute::kind_copy);
   if (GenSetProperty && !objcSetPropertyDefined) {
     objcSetPropertyDefined = true;
     // FIXME. Is this attribute correct in all cases?
@@ -1022,11 +1023,11 @@
     Setr += ", (id)";
     Setr += PD->getName();
     Setr += ", ";
-    if (Attributes & ObjCPropertyDecl::OBJC_PR_nonatomic)
+    if (Attributes & ObjCPropertyAttribute::kind_nonatomic)
       Setr += "0, ";
     else
       Setr += "1, ";
-    if (Attributes & ObjCPropertyDecl::OBJC_PR_copy)
+    if (Attributes & ObjCPropertyAttribute::kind_copy)
       Setr += "1)";
     else
       Setr += "0)";