Override nimcache here too

Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -227,7 +227,7 @@ $(OUTDIR_LIBEXEC)/urldec: $(OUTDIR_LIBEXEC)/urlenc
 
 # Do not add FLAGS here, because that breaks cross-compilation.
 $(OBJDIR)/chac: src/chac.nim lib/monoucha0/monoucha/* lib/monoucha0/monoucha/qjs/*
-	$(NIMC) -o:$@ $<
+	$(NIMC) --nimcache:"$(OBJDIR)/$(TARGET)/chac" -o:$@ $<
 
 $(OUTDIR_LIBEXEC)/%.jsb: src/%.js $(OBJDIR)/chac
 	$(OBJDIR)/chac $(chac_flags) $< $@
