abis/linux: correct type of sigset_t #3239

Job	Run time
Build mlibc (x86_64, mlibc)	9m 26s
Build mlibc (x86_64, mlibc-static)	2m 0s
Compile sysdeps (dripos)	1m 22s
Build mlibc (x86_64, mlibc-shared)	1m 58s
Compile sysdeps (lemon)	1m 1s
Build mlibc (x86_64, mlibc-ansi-only)	1m 54s
Compile sysdeps (aero)	1m 4s
Build mlibc (x86_64, mlibc-headers-only)	1m 10s
Compile sysdeps (ironclad)	57s
Compile sysdeps (lyre)	57s
Build mlibc (riscv64, mlibc)	2m 15s
Compile sysdeps (keyronex)	1m 0s
Build mlibc (riscv64, mlibc-static)	3m 9s
Build mlibc (riscv64, mlibc-shared)	2m 2s
Build mlibc (riscv64, mlibc-ansi-only)	2m 4s
Build mlibc (riscv64, mlibc-headers-only)	1m 6s
Build mlibc (aarch64, mlibc)	2m 41s
Build mlibc (aarch64, mlibc-static)	2m 8s
Build mlibc (aarch64, mlibc-shared)	2m 4s
Build mlibc (aarch64, mlibc-ansi-only)	2m 5s
Build mlibc (aarch64, mlibc-headers-only)	1m 9s
	43m 32s

Provide feedback