Compilation erros on Debian

Debian SID
ldd (Debian GLIBC 2.41-12) 2.41
gcc (Debian 15.2.0-9) 15.2.0
kernel 6.12.9-amd64

1. implicit declaration of function  'strdup' - just a guess, but since it was moved to std lib in c22, it might be hidden then compiling for C99?
2. implicit declaration of function 'posix_memalign' - seems -std=c99 behavior was change in gcc14
3. No <sys/sysctl.h> - depreciated since glibc 2.32