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/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 54ba638..07ba5d3 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -42,7 +42,7 @@
   LexicalScopes.cpp
   LiveDebugValues.cpp
   LiveDebugVariables.cpp
-  LiveIntervalAnalysis.cpp
+  LiveIntervals.cpp
   LiveInterval.cpp
   LiveIntervalUnion.cpp
   LivePhysRegs.cpp