Revert "Adding DIImportedModules to DIScopes."

This reverts commit 342d92c7a0.

Turns out we're going with a different schema design to represent
DW_TAG_imported_modules so we won't need this extra field.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178215 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/DIBuilder.h

@@ -46,7 +46,6 @@ namespace llvm {
   class DITemplateTypeParameter;
   class DITemplateValueParameter;
   class DIObjCProperty;
-  class DIImportedModule;
 
   class DIBuilder {
     private:
@@ -567,11 +566,6 @@ namespace llvm {
     DILexicalBlock createLexicalBlock(DIDescriptor Scope, DIFile File,
                                       unsigned Line, unsigned Col);
 
-
-    /// \brief Create a descriptor for an imported module.
-    /// @param NS The namespace being imported here
-    DIImportedModule createImportedModule(DINameSpace NS);
-
     /// insertDeclare - Insert a new llvm.dbg.declare intrinsic call.
     /// @param Storage     llvm::Value of the variable
     /// @param VarInfo     Variable's debug info descriptor.