make -print-machineinstrs work for both SparcV9 and X86

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12122 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetMachineImpls.h

@@ -16,6 +16,10 @@
 #define LLVM_TARGET_TARGETMACHINEIMPLS_H
 
 namespace llvm {
+  /// Command line options shared between TargetMachine implementations - 
+  /// these should go in their own header eventually.
+  ///
+  extern bool PrintMachineCode;
 
   class TargetMachine;
   class Module;