ovsdb-idl: Fix use of uninitialized datum for graph consistency check. #2538

Job	Run time
linux deb no dpdk	5m 14s
libreswan (ubuntu-24.04)	8s
linux rpm fedora	4m 8s
dpdk gcc (ubuntu-24.04)	7s
build oss-fuzz fuzzers	2m 54s
osx clang --disable-ssl	1m 48s
clang-analyze	20m 40s
linux gcc --disable-ssl	2m 49s
linux clang --disable-ssl	2m 31s
linux gcc c99	2m 34s
linux clang c99	2m 36s
linux gcc test	8m 30s
linux clang address,undefined test	16m 14s
linux gcc test --enable-shared	11m 15s
linux clang test --enable-shared	10m 49s
linux gcc check check-dpdk dpdk	15m 32s
linux clang check check-dpdk dpdk	15m 27s
linux gcc test -ljemalloc	8m 44s
linux clang test -ljemalloc	8m 39s
linux gcc --enable-afxdp	2m 45s
linux clang --enable-afxdp	2m 33s
linux gcc dpdk --enable-shared	3m 56s
linux clang dpdk --enable-shared	3m 43s
linux gcc dpdk-shared	2m 59s
linux clang dpdk-shared	2m 46s
linux gcc dpdk-shared --enable-shared	4m 7s
linux clang dpdk-shared --enable-shared	3m 56s
linux gcc m32 --disable-ssl	2m 30s
linux gcc check-ovsdb-cluster	6m 54s
linux gcc check-kernel -100	10m 43s
linux gcc check-kernel 100-	6m 0s
linux clang address,undefined check-kernel -100	13m 16s
linux clang address,undefined check-kernel 100-	7m 29s
linux gcc check-offloads -100	10m 9s
linux gcc check-offloads 100-	6m 56s
linux gcc dpdk check-system-userspace	8m 52s
linux clang address,undefined dpdk check-system-userspace	11m 47s
linux gcc dpdk check-system-tso	8m 53s
linux gcc dpdk check-afxdp	8m 59s
	4h 29m 52s

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