Use a separate variable for the target as the link-time object file.

Put that in your pipeline and smoke it.

src/conio/Common.gmake

@@ -176,4 +176,5 @@ endif
 
 ifdef NEED_BITMAP
  CIOLIB_INTERPOLATE_OBJS = $(CIOLIB_SRC)$(DIRSEP)$(MTOBJODIR)$(DIRSEP)rgbmap$(OFILE)
+ CIOLIB_INTERPOLATE_TARGET = $(MTOBJODIR)$(DIRSEP)rgbmap$(OFILE)
 endif

src/conio/GNUmakefile

@@ -48,7 +48,7 @@ endif
 
 
 # CIOLIB Library Link Rule
-$(CIOLIB-MT_BUILD): $(MTOBJODIR) $(OBJS) $(CIOLIB_INTERPOLATE_OBJS)
+$(CIOLIB-MT_BUILD): $(MTOBJODIR) $(OBJS) $(CIOLIB_INTERPOLATE_TARGET)
 	@echo Creating $@ ...
 	$(QUIET)$(AR) rc $@ $(OBJS)
 	$(QUIET)$(RANLIB) $@