Fix compilation on Cygwin (again) after #476 - #503

$ make
[ 10%] Linking C executable osslsigncode.exe
/usr/lib/gcc/x86_64-pc-cygwin/14/../../../../x86_64-pc-cygwin/bin/ld: unrecognized option '-z'
/usr/lib/gcc/x86_64-pc-cygwin/14/../../../../x86_64-pc-cygwin/bin/ld: use the --help option for usage information
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/osslsigncode.dir/build.make:231: osslsigncode.exe] Error 1
make[1]: *** [CMakeFiles/Makefile2:89: CMakeFiles/osslsigncode.dir/all] Error 2
make: *** [Makefile:166: all] Error 2