Fix building with enabling ssl on cygwin

[fd00]

$ uname -srvmpio
CYGWIN_NT-10.0-22000-ARM64 3.6.3-1.x86_64 2025-06-05 11:45 UTC x86_64 unknown unknown Cygwin
$ cd /tmp
$ git clone https://github.com/redis/hiredis.git
$ cd hiredis
$ cmake -DENABLE_SSL:BOOL=ON .
$ make
:
[ 83%] Linking C shared library cyghiredis_ssl-1.dll
/usr/lib/gcc/x86_64-pc-cygwin/12/../../../../x86_64-pc-cygwin/bin/ld: CMakeFiles/hiredis_ssl.dir/ssl.c.o:ssl.c:(.text+0x658): undefined reference to `__redisSetError'
:
(snip)
:
/usr/lib/gcc/x86_64-pc-cygwin/12/../../../../x86_64-pc-cygwin/bin/ld: CMakeFiles/hiredis_ssl.dir/ssl.c.o:ssl.c:(.rdata$.refptr.hiredisAllocFns[.refptr.hiredisAllocFns]+0x0): undefined reference to `hiredisAllocFns'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/hiredis_ssl.dir/build.make:99: cyghiredis_ssl-1.dll] Error 1
make[1]: *** [CMakeFiles/Makefile2:113: CMakeFiles/hiredis_ssl.dir/all] Error 2
make: *** [Makefile:166: all] Error 2
$

[fd00]

Sorry I forgot to disable Automatic Copilot code review.