dix: Fix a warning about GetTimeInMillis return value in XFont2. #228

Job	Run time
Build on ubuntu:20.04 - gcc	8m 23s
Build on ubuntu:20.04 - clang	8m 14s
Build on ubuntu:22.04 - gcc	7m 46s
Build on ubuntu:22.04 - clang	8m 18s
Build on ubuntu:24.04 - gcc	8m 27s
Build on ubuntu:24.04 - clang	9m 3s
Build on debian:stable - gcc	8m 34s
Build on debian:stable - clang	8m 48s
Build on debian:sid - gcc	8m 20s
Build on debian:sid - clang	9m 7s
Build on quay.io/rockylinux/rockylinux:8 - gcc	7m 59s
Build on quay.io/rockylinux/rockylinux:8 - clang	9m 32s
Build on quay.io/centos/centos:stream9 - gcc	8m 51s
Build on quay.io/centos/centos:stream9 - clang	9m 8s
Build on fedora:latest - gcc	8m 37s
Build on fedora:latest - clang	8m 29s
	2h 17m 36s

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