Emit an error if we're trying to build GHC from source without GHC installed.
+dnl ** Must have GHC to build GHC, unless --enable-hc-boot is on
+if test "$BootingFromHc" = "NO" -a "$WithGhc" = "" -a -d "$srcdir/ghc"; then
+AC_MSG_ERROR([GHC is required unless bootstrapping from .hc files.])
+fi;
dnl ** Enable multi-thread friendly RTS?
dnl --------------------------------------------------------------
dnl ** Enable multi-thread friendly RTS?
dnl --------------------------------------------------------------