Add libnsl-devel to Cygwin packages we need

Author: bingos

.github/workflows/smoke-windows-cygwin.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Set up Cygwin
         run: |
           choco install cygwin cyg-get
-          cyg-get cygwin-devel gcc-core gcc gcc-g++ make cygwin64-w32api-headers binutils libtool git perl libcrypt-devel
+          cyg-get cygwin-devel gcc-core gcc gcc-g++ make cygwin64-w32api-headers binutils libtool git perl libcrypt-devel libnsl-devel
       - name: Find out environment
         shell: cmd
         run: |