Rename -ddump-cmm-rewrite to -ddump-cmm-sink

This makes it consistent with the corresponding -cmm-sink flag

compiler/cmm/CmmPipeline.hs

@@ -99,7 +99,7 @@ cpsTop hsc_env proc =
        ----------- Sink and inline assignments  --------------------------------
        g <- {-# SCC "sink" #-} -- See Note [Sinking after stack layout]
             condPass Opt_CmmSink (cmmSink dflags) g
-                     Opt_D_dump_cmm_rewrite "Sink assignments"
+                     Opt_D_dump_cmm_sink "Sink assignments"
 
        ------------- CAF analysis ----------------------------------------------
        let cafEnv = {-# SCC "cafAnal" #-} cafAnal g

compiler/main/DynFlags.hs

@@ -197,7 +197,7 @@ data DumpFlag
    | Opt_D_dump_cmm_cfg
    | Opt_D_dump_cmm_cbe
    | Opt_D_dump_cmm_proc
-   | Opt_D_dump_cmm_rewrite
+   | Opt_D_dump_cmm_sink
    | Opt_D_dump_cmm_sp
    | Opt_D_dump_cmm_procmap
    | Opt_D_dump_cmm_split
@@ -2220,7 +2220,7 @@ dynamic_flags = [
   , Flag "ddump-cmm-cfg"           (setDumpFlag Opt_D_dump_cmm_cfg)
   , Flag "ddump-cmm-cbe"           (setDumpFlag Opt_D_dump_cmm_cbe)
   , Flag "ddump-cmm-proc"          (setDumpFlag Opt_D_dump_cmm_proc)
-  , Flag "ddump-cmm-rewrite"       (setDumpFlag Opt_D_dump_cmm_rewrite)
+  , Flag "ddump-cmm-sink"          (setDumpFlag Opt_D_dump_cmm_sink)
   , Flag "ddump-cmm-sp"            (setDumpFlag Opt_D_dump_cmm_sp)
   , Flag "ddump-cmm-procmap"       (setDumpFlag Opt_D_dump_cmm_procmap)
   , Flag "ddump-cmm-split"         (setDumpFlag Opt_D_dump_cmm_split)