Factor some of the constants+context related code out into a separate header, to make LLVMContextImpl.h
not hideous.  Also, fix some MSVC compile errors.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78115 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Archive/ArchiveInternals.h b/lib/Archive/ArchiveInternals.h
index d187ed9..98f9c89 100644
--- a/lib/Archive/ArchiveInternals.h
+++ b/lib/Archive/ArchiveInternals.h
@@ -31,7 +31,7 @@
 
 namespace llvm {
 
-  class LLVMContext;
+  struct LLVMContext;
 
   /// The ArchiveMemberHeader structure is used internally for bitcode
   /// archives.