Undefined reference error occurred when compiling ld dir

[iiicp]

gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)

1. cd aqcc/ld dir
2. make

The following error occurred:

/usr/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400144
/tmp/ccs55tqL.o: In function exit': /home/xxxx/compiler/aqcc/ld/stdlib.c:113: undefined reference to syscall'
/tmp/ccs55tqL.o: In function brk': /home/xxxx/compiler/aqcc/ld/stdlib.c:120: undefined reference to syscall'
/tmp/ccs55tqL.o: In function open': /home/xxxx/compiler/aqcc/ld/stdlib.c:150: undefined reference to syscall'
/tmp/ccs55tqL.o: In function close': /home/xxxx/compiler/aqcc/ld/stdlib.c:153: undefined reference to syscall'
/tmp/ccs55tqL.o: In function write': /home/xxxx/compiler/aqcc/ld/stdlib.c:161: undefined reference to syscall'
/tmp/ccs55tqL.o:/home/xxxx/compiler/aqcc/ld/stdlib.c:166: more undefined references to `syscall' follow
collect2: error: ld returned 1 exit status
Makefile:8: recipe for target 'ld' failed

[ushitora-anqou]

Hmm, that's strange. Maybe gcc is not correctly installed? I'm not sure.