__GHC_PATCHLEVEL__ is set by compat/Makefile to be equal to
GhcPatchLevel, which seems to be set to the patch level of the
INSTALLED Ghc compiler. If there is no installed Ghc compiler,
__GHC_PATCHLEVEL__ is blank and unicode.c fails to compile because &&
wants another operand.
I took the lazy to this by setting GhcPatchLevel in my mk/build.mk file.