virtiofsd: fix the build on ppc64le

link-self-contained is not supported on ppc64le rust target.
Hence, do not pass it while building virtiofsd.

Fixes: #6195

Backport of #856ab66871

Signed-off-by: Amulyam24 <amulmek1@in.ibm.com>
Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>

tools/packaging/static-build/virtiofsd/build-static-virtiofsd.sh

@@ -57,6 +57,7 @@ init_env() {
        LIBC="gnu"
        ARCH="powerpc64le"
        ARCH_LIBC=${ARCH}-linux-${LIBC}
+       extra_rust_flags=""
      ;;
      "s390x")
        LIBC="gnu"