gitlab-ci: Don't FORCE_SYMLINKS on Windows

Not all runners have symlink permissions enabled.

.gitlab-ci.yml

@@ -791,7 +791,7 @@ validate-x86_64-linux-fedora27:
     - bash -c 'make clean || true'
   dependencies: []
   variables:
-    FORCE_SYMLINKS: 1
+    #FORCE_SYMLINKS: 1
     LANG: "en_US.UTF-8"
     SPHINXBUILD: "/mingw64/bin/sphinx-build.exe"
   cache: