Subzero: Remove the IceV_RegManager enum value.

This hasn't been used in a very long time, and there's no intention of using it again.

Originally there was the idea of a "fast" block-local register allocator for an O1-like configuration, which would allocate registers for infinite-weight temporaries during target lowering, using a "local register manager".  This verbose option was for tracing execution of this register manager.  However, by now it seems unlikely that this would do a better/faster job than the current Om1 register allocation approach, which reuses the linear-scan code quite effectively and does very well at separation of concerns.  So adios IceV_RegManager!

BUG= none
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/831663008
diff --git a/src/IceDefs.h b/src/IceDefs.h
index 4f58ede..cd4011b 100644
--- a/src/IceDefs.h
+++ b/src/IceDefs.h
@@ -148,12 +148,11 @@
   IceV_Preds = 1 << 3,
   IceV_Succs = 1 << 4,
   IceV_Liveness = 1 << 5,
-  IceV_RegManager = 1 << 6,
-  IceV_RegOrigins = 1 << 7,
-  IceV_LinearScan = 1 << 8,
-  IceV_Frame = 1 << 9,
-  IceV_AddrOpt = 1 << 10,
-  IceV_Random = 1 << 11,
+  IceV_RegOrigins = 1 << 6,
+  IceV_LinearScan = 1 << 7,
+  IceV_Frame = 1 << 8,
+  IceV_AddrOpt = 1 << 9,
+  IceV_Random = 1 << 10,
   IceV_All = ~IceV_None,
   IceV_Most = IceV_All & ~IceV_LinearScan
 };