Fix wraparound in SstFileManager #2759

Job	Run time
build-linux-cmake-with-folly	27m 55s
build-linux	17m 36s
build-linux-cmake-with-folly-lite-no-test	7m 47s
build-linux-cmake-mingw	12m 20s
build-linux-cmake-with-folly-coroutines	31m 36s
build-linux-cmake-with-benchmark	19m 13s
build-linux-encrypted_env-no_compression	16m 56s
build-linux-make-with-folly	27m 44s
build-linux-make-with-folly-lite-no-test	9m 16s
check-format-and-targets	21s
build-examples	11m 10s
build-fuzzers	8m 34s
build-linux-arm	14m 8s
build-linux-clang10-asan	16m 39s
build-linux-clang10-clang-analyze	17m 38s
build-linux-clang10-mini-tsan	24m 4s
build-linux-clang10-ubsan	16m 42s
build-linux-clang-13-no_test_run	7m 9s
build-linux-clang-no_test_run	11m 36s
build-linux-gcc-11-no_test_run	9m 52s
build-linux-gcc-10-cxx20-no_test_run	9m 30s
build-linux-gcc-8-no_test_run	8m 31s
build-linux-java	14m 55s
build-linux-java-pmd	12m 0s
build-linux-java-static	11m 40s
build-linux-mini-crashtest	28m 59s
build-linux-release	14m 4s
build-linux-release-rtti	12m 15s
build-linux-static_lib-alt_namespace-status_checked	18m 54s
build-linux-unity-and-headers	12m 57s
build-macos	18m 17s
build-macos-cmake (true)	45m 36s
build-macos-java	15m 45s
build-macos-cmake (false)	35m 56s
build-macos-java-static	20m 16s
build-macos-java-static-universal	20m 15s
build-windows-vs2019	52m 45s
	11h 0m 51s

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