Thank you for the report. Well, it seems that intrflush has moved from ncurses.so to tinfo.so in 5.6 or 5.7.
Thus, despite the man page says "-lncurses", it seems that we also need "-ltinfo" when building for recent distributions.
# nm -D /usr/lib/libncurses.so.5.3 | grep intr
0002a5a0 T intrflush
# nm -D /usr/lib/libncurses.so.5.4 | grep intr
0002b10e T intrflush
# nm -D /usr/lib/libncurses.so.5.5 | grep intr
00413ee0 T intrflush
# nm -D /lib/libncurses.so.5.7 | grep intr
# nm -D /lib/libtinfo.so.5.7 | grep intr
00008d50 T intrflush
# nm -D /usr/lib64/libncurses.so.5.9 | grep intr
# nm -D /usr/lib64/libtinfo.so.5.9 | grep intr
0000000000011330 T intrflush
Please use ccs-tools-1.8.6-20200229.tar.gz . Thank you.
ccs-tools 1.8.6 build error
https://pastebin.com/2y0xvhVB
Adding -ltinfo to the LDFLAGS fix this error, not sure if it's the right fix however.