Pass -this-unit-id because cabal doesn't when it compiles Cmm files

Author: hsyl20

Makefile

@@ -194,6 +194,7 @@ _build/stage1/bin/ghc: _build/stage0/bin/ghc
 	  --ghc-options='"-optc=-DTargetVendor=\"FIXME\""' \
 	  --ghc-options='"-optc=-DGhcUnregisterised=\"FIXME\""' \
 	  --ghc-options='"-optc=-DTablesNextToCode=\"FIXME\""' \
+	  --ghc-options='-this-unit-id rts' \
 	  --builddir=_build/stage1/cabal/
 
 clean: