Various fixes and stubs to the posix option for systemd #4211

Job	Run time
Compile sysdeps (dripos)	1m 58s
Compile sysdeps (lemon)	1m 59s
Build mlibc (x86_64, mlibc, gcc)	2m 10s
Compile sysdeps (aero)	2m 3s
Compile sysdeps (ironclad)	1m 56s
Build mlibc (x86_64, mlibc-static, gcc)	1s
Compile sysdeps (lyre)	2m 1s
Build mlibc (x86_64, mlibc-shared, gcc)	1s
Compile sysdeps (keyronex)	2m 0s
Build mlibc (x86_64, mlibc-ansi-only, gcc)	2m 9s
Build mlibc (x86_64, mlibc-headers-only, gcc)	2m 4s
Build mlibc (riscv64, mlibc, gcc)	2m 10s
Compile sysdeps (managarm)	2m 2s
Compile sysdeps (vinix)	1m 58s
Build mlibc (riscv64, mlibc-static, gcc)	2m 3s
Compile sysdeps (astral)	2m 7s
Build mlibc (riscv64, mlibc-shared, gcc)	2m 10s
Build mlibc (riscv64, mlibc-ansi-only, gcc)	2m 11s
Build mlibc (riscv64, mlibc-headers-only, gcc)	2m 6s
Build mlibc (aarch64, mlibc, gcc)	2m 13s
Build mlibc (aarch64, mlibc-static, gcc)	2m 12s
Build mlibc (aarch64, mlibc-shared, gcc)	2m 11s
Build mlibc (aarch64, mlibc-ansi-only, gcc)	2m 10s
Build mlibc (aarch64, mlibc-headers-only, gcc)	2m 12s
Build mlibc (x86, mlibc, gcc)	1s
Build mlibc (x86, mlibc-static, gcc)	1s
Build mlibc (x86, mlibc-shared, gcc)	1s
Build mlibc (x86, mlibc-ansi-only, gcc)	1s
Build mlibc (x86, mlibc-headers-only, gcc)	1s
Build mlibc (m68k, mlibc, gcc)	2m 13s
Build mlibc (m68k, mlibc-static, gcc)	2m 9s
Build mlibc (m68k, mlibc-shared, gcc)	2m 10s
Build mlibc (m68k, mlibc-ansi-only, gcc)	2m 10s
Build mlibc (m68k, mlibc-headers-only, gcc)	2m 9s
Build mlibc (x86_64, mlibc, clang)	2m 9s
	59m 12s

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