.gitlab-ci.yml: link with shared library on x86-64 build

This allows testing whether exported symbols are sufficient for the
included test suite.

.gitlab-ci.yml

@@ -13,7 +13,7 @@ build/x86-64:
   image: $CI_REGISTRY/$BUILD_IMAGES_PROJECT:$FEDORA_BUILD
   script:
   - ./.bootstrap &&
-    ./configure --enable-fat --disable-documentation && make -j4 &&
+    ./configure --disable-static --enable-fat --disable-documentation && make -j4 &&
     make check -j4
   tags:
   - shared