fix missing va_end #81

Job	Run time
Dockerfile_openexr3-repo-root	6m 50s
Dockerfile-repo-root	4m 31s
fedora-36	2m 42s
fedora-37	2m 42s
redhat-ubi8	4m 34s
redhat-ubi9	5m 29s
ubuntu-18-04	1m 25s
ubuntu-20-04	1m 32s
ubuntu-22-04	1m 29s
ubuntu-22-04-LTO	2m 15s
ubuntu-23-10	6s
ubuntu-latest	1m 53s
fedora-38	2m 56s
fedora-latest	2m 53s
ubuntu-22-04-openexr33	3m 53s
ubuntu-openexr2-shared	2m 47s
ubuntu-openexr2-static	2m 49s
	50m 46s

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