fail to compile on cygwin

Here is the message I got during compilation. I checked /usr/include and
do not see libgen.h there.

Thanks for help.
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hdup version: 1.6.33
make[1]: Entering directory `/home/btang/hdup16/src'
gcc -Wall -g -O2 -DHAVE_CONFIG_H -D_FILE_OFFSET_BITS=64 -D_LARGE_FILES
-Wpointer-arith -Wstrict-prototypes   -c hdup.c
In file included from hdup.h:12,
                 from hdup.c:25:
config.h:26:20: libgen.h: No such file or directory
hdup.c: In function `main':
hdup.c:581: warning: implicit declaration of function `basename'
hdup.c:581: warning: passing arg 1 of `openlog' makes pointer from integer
without a cast
make[1]: *** [hdup.o] Error 1
make[1]: Leaving directory `/home/btang/hdup16/src'
make: *** [hdup] Error 2