sysdeps/managarm: make RISC-V compile and link #4170

Job	Run time
Compile sysdeps (dripos)	2m 18s
Compile sysdeps (lemon)	2m 27s
Build mlibc (x86_64, mlibc, gcc)	4m 4s
Compile sysdeps (aero)	2m 23s
Build mlibc (x86_64, mlibc-static, gcc)	3m 10s
Compile sysdeps (ironclad)	2m 43s
Build mlibc (x86_64, mlibc-shared, gcc)	2m 59s
Build mlibc (x86_64, mlibc-ansi-only, gcc)	2m 52s
Compile sysdeps (lyre)	2m 17s
Build mlibc (x86_64, mlibc-headers-only, gcc)	2m 0s
Compile sysdeps (keyronex)	2m 27s
Build mlibc (riscv64, mlibc, gcc)	4m 0s
Compile sysdeps (managarm)	2m 39s
Build mlibc (riscv64, mlibc-static, gcc)	5m 7s
Compile sysdeps (vinix)	2m 24s
Build mlibc (riscv64, mlibc-shared, gcc)	3m 20s
Compile sysdeps (astral)	2m 46s
Build mlibc (riscv64, mlibc-ansi-only, gcc)	2m 45s
Build mlibc (riscv64, mlibc-headers-only, gcc)	1m 57s
Build mlibc (aarch64, mlibc, gcc)	4m 0s
Build mlibc (aarch64, mlibc-static, gcc)	3m 42s
Build mlibc (aarch64, mlibc-shared, gcc)	3m 27s
Build mlibc (aarch64, mlibc-ansi-only, gcc)	3m 5s
Build mlibc (aarch64, mlibc-headers-only, gcc)	2m 0s
Build mlibc (x86, mlibc, gcc)	3m 56s
Build mlibc (x86, mlibc-static, gcc)	3m 22s
Build mlibc (x86, mlibc-shared, gcc)	3m 26s
Build mlibc (x86, mlibc-ansi-only, gcc)	3m 3s
Build mlibc (x86, mlibc-headers-only, gcc)	2m 0s
Build mlibc (m68k, mlibc, gcc)	3m 48s
Build mlibc (m68k, mlibc-static, gcc)	2m 54s
Build mlibc (m68k, mlibc-shared, gcc)	2m 51s
Build mlibc (m68k, mlibc-ansi-only, gcc)	2m 50s
Build mlibc (m68k, mlibc-headers-only, gcc)	1m 55s
Build mlibc (x86_64, mlibc, clang)	3m 18s
	1h 44m 15s

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