various fixes for failing GMP tests #4301

Job	Run time
Compile sysdeps (dripos)	2m 26s
Compile sysdeps (lemon)	2m 26s
Build mlibc (x86_64, mlibc, gcc)	6s
Compile sysdeps (aero)	2m 51s
Build mlibc (x86_64, mlibc-static, gcc)	1s
Compile sysdeps (ironclad)	2m 50s
Build mlibc (x86_64, mlibc-shared, gcc)	4s
Compile sysdeps (lyre)	2m 47s
Build mlibc (x86_64, mlibc-ansi-only, gcc)	6s
Compile sysdeps (keyronex)	2m 27s
Build mlibc (x86_64, mlibc-headers-only, gcc)	8s
Compile sysdeps (managarm)	2m 40s
Build mlibc (riscv64, mlibc, gcc)	53s
Compile sysdeps (vinix)	2m 50s
Build mlibc (riscv64, mlibc-static, gcc)	17s
Compile sysdeps (astral)	2m 55s
Build mlibc (riscv64, mlibc-shared, gcc)	20s
Build mlibc (riscv64, mlibc-ansi-only, gcc)	31s
Build mlibc (riscv64, mlibc-headers-only, gcc)	30s
Build mlibc (aarch64, mlibc, gcc)	3m 5s
Build mlibc (aarch64, mlibc-static, gcc)	3m 4s
Build mlibc (aarch64, mlibc-shared, gcc)	3m 3s
Build mlibc (aarch64, mlibc-ansi-only, gcc)	3m 4s
Build mlibc (aarch64, mlibc-headers-only, gcc)	2m 33s
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)	3m 4s
Build mlibc (m68k, mlibc-static, gcc)	34s
Build mlibc (m68k, mlibc-shared, gcc)	2m 37s
Build mlibc (m68k, mlibc-ansi-only, gcc)	2m 58s
Build mlibc (m68k, mlibc-headers-only, gcc)	2m 39s
Build mlibc (x86_64, mlibc, clang)	8s
	54m 2s

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