[CI] Fix build error.

Author: qiaojbao

docker/amdvlk.Dockerfile

@@ -73,7 +73,7 @@ COPY docker/update-llpc.sh /vulkandriver/
 WORKDIR /vulkandriver/builds/ci-build
 RUN EXTRA_COMPILER_FLAGS=() \
     && EXTRA_LINKER_FLAGS=() \
-    && EXTRA_FLAGS=("") \
+    && EXTRA_FLAGS=() \
     && SANITIZERS=() \
     && if echo "$FEATURES" | grep -q "+gcc" ; then \
          EXTRA_FLAGS+=("-DCMAKE_C_COMPILER=gcc"); \