Remove warning about declaration does not declare anything. This class was

already declared in the other headers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60261 91177308-0d34-0410-b5e6-96231b3b80d8

tools/lto/LTOCodeGenerator.h

@@ -26,7 +26,6 @@
 // C++ class which implements the opaque lto_code_gen_t
 //
 
-class llvm::raw_ostream;
 class LTOCodeGenerator {
 public:
     static const char*        getVersionString();