Rename LiveIntervalAnalysis.h to LiveIntervals.h

Headers/Implementation files should be named after the class they
declare/define.

Also eliminated an `#include "llvm/CodeGen/LiveIntervalAnalysis.h"` in
favor of `class LiveIntarvals;`

llvm-svn: 320546
diff --git a/llvm/lib/CodeGen/RenameIndependentSubregs.cpp b/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
index b423d67..1e1f36a 100644
--- a/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
+++ b/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
@@ -30,7 +30,7 @@
 #include "LiveRangeUtils.h"
 #include "PHIEliminationUtils.h"
 #include "llvm/CodeGen/LiveInterval.h"
-#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/LiveIntervals.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"