tor FTBFS on clang/i386

https://jenkins.torproject.org/job/tor-ci-linux-master-clang/ARCHITECTURE=i386,SUITE=sid/1905/consoleFull

21:22:55 mv -f $depbase.Tpo $depbase.Po
21:22:55 src/common/storagedir.c:209:18: error: implicit conversion loses integer precision: '__off64_t' (aka 'long long') to 'size_t' (aka 'unsigned int') [-Werror,-Wshorten-64-to-32]
21:22:55     *sz_out = st.st_size;
21:22:55             ~ ~~~^~~~~~~
21:22:55 1 error generated.
21:22:55 Makefile:4834: recipe for target 'src/common/storagedir.o' failed
21:22:55 make[1]: *** [src/common/storagedir.o] Error 1