Remove the ASTContext parameter from the attribute-related methods of Decl.
The implementations of these methods can Use Decl::getASTContext() to get the ASTContext.

This commit touches a lot of files since call sites for these methods are everywhere.
I used pre-tokenized "carbon.h" and "cocoa.h" headers to do some timings, and there was no real time difference between before the commit and after it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74501 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/CheckObjCUnusedIVars.cpp b/lib/Analysis/CheckObjCUnusedIVars.cpp
index 21dc658..a68c82f 100644
--- a/lib/Analysis/CheckObjCUnusedIVars.cpp
+++ b/lib/Analysis/CheckObjCUnusedIVars.cpp
@@ -73,7 +73,7 @@
       continue;
 
     // Skip IB Outlets.
-    if (ID->getAttr<IBOutletAttr>(Ctx))
+    if (ID->getAttr<IBOutletAttr>())
       continue;
     
     M[ID] = Unused;