Implement various syscalls on Linux for systemd #4254

Job	Run time
Build mlibc (x86_64, mlibc, gcc)	3m 47s
Compile sysdeps (dripos)	2m 21s
Build mlibc (x86_64, mlibc-static, gcc)	3m 6s
Compile sysdeps (lemon)	2m 23s
Build mlibc (x86_64, mlibc-shared, gcc)	3m 13s
Compile sysdeps (aero)	2m 22s
Build mlibc (x86_64, mlibc-ansi-only, gcc)	2m 53s
Compile sysdeps (ironclad)	2m 20s
Build mlibc (x86_64, mlibc-headers-only, gcc)	2m 3s
Compile sysdeps (lyre)	2m 19s
Build mlibc (riscv64, mlibc, gcc)	3m 58s
Compile sysdeps (keyronex)	2m 18s
Build mlibc (riscv64, mlibc-static, gcc)	4m 42s
Build mlibc (riscv64, mlibc-shared, gcc)	3m 7s
Build mlibc (riscv64, mlibc-ansi-only, gcc)	2m 56s
Compile sysdeps (managarm)	2m 45s
Build mlibc (riscv64, mlibc-headers-only, gcc)	1m 57s
Compile sysdeps (vinix)	2m 23s
Build mlibc (aarch64, mlibc, gcc)	4m 6s
Compile sysdeps (astral)	2m 20s
Build mlibc (aarch64, mlibc-static, gcc)	3m 28s
Build mlibc (aarch64, mlibc-shared, gcc)	3m 23s
Build mlibc (aarch64, mlibc-ansi-only, gcc)	3m 2s
Build mlibc (aarch64, mlibc-headers-only, gcc)	2m 2s
Build mlibc (x86, mlibc, gcc)	4m 35s
Build mlibc (x86, mlibc-static, gcc)	3m 15s
Build mlibc (x86, mlibc-shared, gcc)	3m 19s
Build mlibc (x86, mlibc-ansi-only, gcc)	3m 8s
Build mlibc (x86, mlibc-headers-only, gcc)	2m 8s
Build mlibc (m68k, mlibc, gcc)	3m 35s
Build mlibc (m68k, mlibc-static, gcc)	2m 59s
Build mlibc (m68k, mlibc-shared, gcc)	2m 59s
Build mlibc (m68k, mlibc-ansi-only, gcc)	2m 53s
Build mlibc (m68k, mlibc-headers-only, gcc)	2m 28s
Build mlibc (x86_64, mlibc, clang)	3m 18s
	1h 43m 51s

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