Add an unregisterised config to build.mk

mk/build.mk.sample

@@ -27,6 +27,9 @@
 # A development build, working on the stage 2 compiler:
 #BuildFlavour = devel2
 
+# An unregisterised, optimised build of ghc, for porting:
+#BuildFlavour = unreg
+
 GhcLibWays = v
 
 # -------- 1. A Performance/Distribution build--------------------------------
@@ -133,6 +136,26 @@ BUILD_DOCBOOK_PDF  = NO
 
 endif
 
+# -------- A Unregisterised build) -------------------------------------------
+
+ifeq "$(BuildFlavour)" "unreg"
+
+GhcUnregisterised    = YES
+GhcWithNativeCodeGen = NO
+
+SRC_HC_OPTS          = -O -H64m
+GhcStage1HcOpts      = -O
+GhcStage2HcOpts      = -O2
+GhcHcOpts            = -Rghc-timing
+GhcLibHcOpts         = -O2
+SplitObjs            = NO
+HADDOCK_DOCS         = NO
+BUILD_DOCBOOK_HTML   = NO
+BUILD_DOCBOOK_PS     = NO
+BUILD_DOCBOOK_PDF    = NO
+
+endif
+
 # -----------------------------------------------------------------------------
 # Other settings that might be useful