Extracts an TargetX86Base target which will be used as the common X86{32,64} implementation.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4077
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1202533003.
diff --git a/src/IceInst.h b/src/IceInst.h
index 2b5adc6..7aad054 100644
--- a/src/IceInst.h
+++ b/src/IceInst.h
@@ -16,6 +16,7 @@
 #ifndef SUBZERO_SRC_ICEINST_H
 #define SUBZERO_SRC_ICEINST_H
 
+#include "IceCfg.h"
 #include "IceDefs.h"
 #include "IceInst.def"
 #include "IceIntrinsics.h"