Replace "-ansi" with "-std=c89" in emul/Makefile

"-ansi" is not supported by tcc, but according to gcc
documentation, "-std=c89" produces identical behavior.

See: https://gcc.gnu.org/onlinedocs/gcc-3.4.2/gcc/Standards.html

emul/Makefile

@@ -12,7 +12,7 @@ forth: forth.c $(OBJS) $(BLKFS)
 
 libz80/libz80.o: libz80/z80.c
 	$(MAKE) -C libz80/codegen opcodes
-	$(CC) -Wall -ansi -g -c -o libz80/libz80.o libz80/z80.c
+	$(CC) -Wall -std=c89 -g -c -o libz80/libz80.o libz80/z80.c
 
 emul.o: emul.c forth.bin $(BLKFS)
 	$(CC) -DFBIN_PATH=\"`pwd`/forth.bin\" -DBLKFS_PATH=\"`pwd`/$(BLKFS)\" -c -o emul.o emul.c