Architecture-generic rtdl rework #3126

Job	Run time
Compile sysdeps (dripos)	1m 48s
Compile sysdeps (lemon)	2m 1s
Compile sysdeps (aero)	1m 27s
Compile sysdeps (ironclad)	1m 27s
Compile sysdeps (lyre)	1m 28s
Compile sysdeps (keyronex)	1m 28s
Build mlibc (x86_64, mlibc)	15m 30s
Build mlibc (x86_64, mlibc-static)	2m 51s
Build mlibc (x86_64, mlibc-shared)	3m 37s
Build mlibc (x86_64, mlibc-ansi-only)	3m 22s
Build mlibc (x86_64, mlibc-headers-only)	1m 30s
Build mlibc (riscv64, mlibc)	3m 40s
Build mlibc (riscv64, mlibc-static)	6m 28s
Build mlibc (riscv64, mlibc-shared)	2m 54s
Build mlibc (riscv64, mlibc-ansi-only)	2m 32s
Build mlibc (riscv64, mlibc-headers-only)	1m 24s
Build mlibc (aarch64, mlibc)	4m 3s
Build mlibc (aarch64, mlibc-static)	4m 15s
Build mlibc (aarch64, mlibc-shared)	3m 1s
Build mlibc (aarch64, mlibc-ansi-only)	2m 49s
Build mlibc (aarch64, mlibc-headers-only)	1m 45s
	1h 9m 20s

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