Point out in the comment for GhcLibHcOpts that it also applies to the
standard library and hslibs.
endif
# Option flags to pass to GHC when it's compiling prelude modules
+# *and* standard library modules (std) *and* modules in hslibs
# Typically these are things like -O or -dcore-lint
# The ones that are *essential* are wired into ghc/lib/Makefile
#