options/posix: add bound checks for dns response parsing #4181

Job	Run time
Compile sysdeps (dripos)	2m 20s
Compile sysdeps (lemon)	2m 22s
Build mlibc (x86_64, mlibc, gcc)	4m 17s
Compile sysdeps (aero)	2m 51s
Build mlibc (x86_64, mlibc-static, gcc)	3m 13s
Compile sysdeps (ironclad)	2m 17s
Build mlibc (x86_64, mlibc-shared, gcc)	3m 10s
Compile sysdeps (lyre)	2m 25s
Build mlibc (x86_64, mlibc-ansi-only, gcc)	2m 54s
Compile sysdeps (keyronex)	2m 20s
Build mlibc (x86_64, mlibc-headers-only, gcc)	1m 57s
Compile sysdeps (managarm)	2m 28s
Build mlibc (riscv64, mlibc, gcc)	3m 45s
Compile sysdeps (vinix)	2m 15s
Build mlibc (riscv64, mlibc-static, gcc)	4m 25s
Compile sysdeps (astral)	2m 17s
Build mlibc (riscv64, mlibc-shared, gcc)	3m 1s
Build mlibc (riscv64, mlibc-ansi-only, gcc)	2m 48s
Build mlibc (riscv64, mlibc-headers-only, gcc)	2m 2s
Build mlibc (aarch64, mlibc, gcc)	3m 57s
Build mlibc (aarch64, mlibc-static, gcc)	3m 15s
Build mlibc (aarch64, mlibc-shared, gcc)	3m 22s
Build mlibc (aarch64, mlibc-ansi-only, gcc)	2m 59s
Build mlibc (aarch64, mlibc-headers-only, gcc)	1m 59s
Build mlibc (x86, mlibc, gcc)	3m 57s
Build mlibc (x86, mlibc-static, gcc)	3m 15s
Build mlibc (x86, mlibc-shared, gcc)	3m 16s
Build mlibc (x86, mlibc-ansi-only, gcc)	3m 1s
Build mlibc (x86, mlibc-headers-only, gcc)	1m 55s
Build mlibc (m68k, mlibc, gcc)	3m 55s
Build mlibc (m68k, mlibc-static, gcc)	2m 52s
Build mlibc (m68k, mlibc-shared, gcc)	2m 52s
Build mlibc (m68k, mlibc-ansi-only, gcc)	2m 48s
Build mlibc (m68k, mlibc-headers-only, gcc)	2m 3s
Build mlibc (x86_64, mlibc, clang)	3m 14s
	1h 41m 47s

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