minor: db_dump: compiler warnings on mips

[karlp]

Same code still exists on master and fixes branches. Probably should be %zu instead of %ld as it's a sizeof/size_t value.

make[5]: Entering directory '/home/karlp/src/smartgate_firmware/openwrt-master/build_dir/target-mips_24kc_musl/mosquitto-nossl/mosquitto-2.0.11/apps/db_dump'
ccache_cc -Os -pipe -mno-branch-likely -mips32r2 -mtune=24kc -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -msoft-float -mips16 -minterlink-mips16 -fmacro-prefix-map=/home/karlp/src/smartgate_firmware/openwrt-master/build_dir/target-mips_24kc_musl/mosquitto-nossl/mosquitto-2.0.11=mosquitto-2.0.11 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro  -I/home/karlp/src/smartgate_firmware/openwrt-master/staging_dir/toolchain-mips_24kc_gcc-8.4.0_musl/usr/include -I/home/karlp/src/smartgate_firmware/openwrt-master/staging_dir/toolchain-mips_24kc_gcc-8.4.0_musl/include/fortify -I/home/karlp/src/smartgate_firmware/openwrt-master/staging_dir/toolchain-mips_24kc_gcc-8.4.0_musl/include  -I../../include -I../../ -I../../lib -I../../src -I../../deps -DWITH_BROKER -DWITH_PERSISTENCE -c db_dump.c -o db_dump.o
db_dump.c: In function 'dump__cfg_chunk_process':
db_dump.c:133:98: warning: format '%ld' expects argument of type 'long int', but argument 4 has type 'unsigned int' [-Wformat=]
   fprintf(stderr, "Error: Incompatible database configuration (dbid size is %d bytes, expected %ld)",
                                                                                                ~~^
                                                                                                %d
     chunk.dbid_size, sizeof(dbid_t));
                      ~~~~~~~~~~~~~~

[ralight]

Thanks, I'll sort it.