[llvm] Stop including llvm/ADT/SparseBitVector.h (NFC)

Identified with clangd.

Author: kazutakahirata

llvm/lib/CodeGen/LiveIntervalUnion.cpp

@@ -14,7 +14,6 @@
 
 #include "llvm/CodeGen/LiveIntervalUnion.h"
 #include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SparseBitVector.h"
 #include "llvm/CodeGen/LiveInterval.h"
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/Support/raw_ostream.h"

llvm/lib/DebugInfo/PDB/Native/NamedStreamMap.cpp

@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/PDB/Native/NamedStreamMap.h"
-#include "llvm/ADT/SparseBitVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/PDB/Native/Hash.h"

llvm/lib/Target/X86/X86FlagsCopyLowering.cpp

@@ -30,7 +30,6 @@
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/SparseBitVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineConstantPool.h"