Fix typo in `mod_tile.c` (#474) #729

Job	Run time
debian:12 (Latest Mapnik) (CMake) (GNU)	15m 0s
macos-13 (CMake) (LLVM)	8m 37s
ubuntu:24.04 (Latest Mapnik) (CMake) (GNU)	14m 44s
macos-14 (CMake) (LLVM)	6m 21s
debian:11 (CMake) (GNU)	3m 33s
macos-15 (CMake) (LLVM)	6m 5s
debian:12 (CMake) (GNU)	3m 38s
fedora:40 (CMake) (GNU)	4m 8s
fedora:41 (CMake) (GNU)	4m 51s
opensuse/leap:15 (CMake) (GNU)	15m 8s
quay.io/centos/centos:stream9 (CMake) (GNU)	11m 51s
ubuntu:22.04 (CMake) (GNU)	3m 21s
debian:unstable (CMake) (GNU)	3m 24s
fedora:rawhide (CMake) (GNU)	3m 12s
ubuntu:devel (CMake) (GNU)	3m 42s
FreeBSD-13.4-STABLE (CMake) (LLVM)	1m 59s
ubuntu:24.04 (Autotools) (GNU)	2m 23s
FreeBSD-14.1-STABLE (CMake) (LLVM)	1m 33s
ubuntu:24.04 (Autotools) (LLVM)	2m 42s
ubuntu:24.04 (CMake) (GNU)	3m 12s
ubuntu:24.04 (CMake) (LLVM)	3m 51s
	2h 3m 15s

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