ftell() not consistent in C11 #19117

Job	Run time
build_cmake (alpine:3.23, false, false)	4m 43s
build_make (ubuntu:25.10)	5m 12s
build_make (alpine:3.23)	5m 36s
build_make (ubuntu:24.04)	4m 32s
build_cmake (ubuntu:24.04, true, true)	5m 27s
build_cmake (ubuntu:25.10, true, true)	5m 42s
	31m 12s

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