snapcraft: Disable libyang CACHE for snap package (Temp workaround)

There seems to be a bug in latest libyang running when running in
a snap container which causes a failure of the cache logic. Disable
CACHE for now as it's not yet needed. Will be re-enabled in a later
release

Signed-off-by: Martin Winter <mwinter@opensourcerouting.org>

snapcraft/snapcraft.yaml.in

@@ -266,6 +266,7 @@ parts:
         configflags:
            - -DCMAKE_INSTALL_PREFIX:PATH=/usr
            - -DENABLE_LYD_PRIV=ON
+           - -DENABLE_CACHE=OFF
            - -DCMAKE_BUILD_TYPE:String="Release"
     frr: 
         after: [rtrlib,libyang]