sysdeps/managarm: Add missing Scrt1.S for aarch64 #3277

Job	Run time
Compile sysdeps (dripos)	2m 24s
Compile sysdeps (lemon)	2m 31s
Build mlibc (x86_64, mlibc)	3m 38s
Compile sysdeps (aero)	2m 21s
Build mlibc (x86_64, mlibc-static)	2m 54s
Compile sysdeps (ironclad)	2m 13s
Build mlibc (x86_64, mlibc-shared)	2m 50s
Compile sysdeps (lyre)	2m 12s
Compile sysdeps (keyronex)	2m 26s
Build mlibc (x86_64, mlibc-ansi-only)	2m 42s
Build mlibc (x86_64, mlibc-headers-only)	1m 43s
Build mlibc (riscv64, mlibc)	3m 36s
Build mlibc (riscv64, mlibc-static)	4m 41s
Build mlibc (riscv64, mlibc-shared)	3m 0s
Build mlibc (riscv64, mlibc-ansi-only)	2m 40s
Build mlibc (riscv64, mlibc-headers-only)	1m 44s
Build mlibc (aarch64, mlibc)	3m 44s
Build mlibc (aarch64, mlibc-static)	3m 6s
Build mlibc (aarch64, mlibc-shared)	3m 18s
Build mlibc (aarch64, mlibc-ansi-only)	3m 1s
Build mlibc (aarch64, mlibc-headers-only)	1m 52s
	58m 36s

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