sysdeps/managarm: Fix crti.S + crtn.S and sys_tcb_set() #4182

Job	Run time
Compile sysdeps (dripos)	1m 10s
Build mlibc (x86_64, mlibc, gcc)	1s
Compile sysdeps (lemon)	1m 9s
Build mlibc (x86_64, mlibc-static, gcc)	1s
Compile sysdeps (aero)	1m 9s
Build mlibc (x86_64, mlibc-shared, gcc)	1s
Compile sysdeps (ironclad)	1m 15s
Build mlibc (x86_64, mlibc-ansi-only, gcc)	1s
Compile sysdeps (lyre)	1m 10s
Build mlibc (x86_64, mlibc-headers-only, gcc)	1s
Compile sysdeps (keyronex)	1m 12s
Compile sysdeps (managarm)	1m 12s
Compile sysdeps (vinix)	1m 12s
Build mlibc (riscv64, mlibc, gcc)	1s
Compile sysdeps (astral)	1m 10s
Build mlibc (riscv64, mlibc-static, gcc)	1s
Build mlibc (riscv64, mlibc-shared, gcc)	1s
Build mlibc (riscv64, mlibc-ansi-only, gcc)	1s
Build mlibc (riscv64, mlibc-headers-only, gcc)	1s
Build mlibc (aarch64, mlibc, gcc)	1m 10s
Build mlibc (aarch64, mlibc-static, gcc)	1m 10s
Build mlibc (aarch64, mlibc-shared, gcc)	1m 7s
Build mlibc (aarch64, mlibc-ansi-only, gcc)	1m 8s
Build mlibc (aarch64, mlibc-headers-only, gcc)	1m 7s
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)	1m 7s
Build mlibc (m68k, mlibc-static, gcc)	1s
Build mlibc (m68k, mlibc-shared, gcc)	59s
Build mlibc (m68k, mlibc-ansi-only, gcc)	1m 10s
Build mlibc (m68k, mlibc-headers-only, gcc)	1m 10s
Build mlibc (x86_64, mlibc, clang)	1s
	21m 4s

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