Adds an over-approximation model for sysconf #8384

Job	Run time
check-docker-image	23m 10s
check-macos-11-make-clang	1h 3m 27s
check-macos-12-cmake-clang	46m 12s
check-string-table	3m 54s
check-ubuntu-20_04-cmake-gcc	34m 12s
check-ubuntu-20_04-cmake-gcc-KNOWNBUG	3m 30s
check-ubuntu-20_04-cmake-gcc-THOROUGH	12m 58s
check-ubuntu-20_04-make-clang	32m 59s
check-ubuntu-20_04-make-clang-smt-z3	4m 46s
check-ubuntu-20_04-make-gcc	19m 58s
check-ubuntu-22_04-cmake-gcc	32m 57s
check-ubuntu-22_04-cmake-gcc-12	26m 53s
check-ubuntu-22_04-make-clang	31m 7s
check-vs-2019-cmake-build-and-test	1h 0m 0s
check-vs-2022-make-build-and-test	52m 44s
windows-msi-package	7m 58s
codecov-coverage-report	51m 40s
include-what-you-use	34m 1s
	9h 2m 26s

Provide feedback