[InstCombine] Remove unused header

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -12,7 +12,6 @@
 
 #include "InstCombineInternal.h"
 #include "llvm/ADT/APInt.h"
-#include "llvm/ADT/FloatingPointMode.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/AssumptionCache.h"