[druntime]: Fix posix.sys.shm.shmid_ds on (some) non-x86_64

Check glibc's sysdeps/unix/sysv/linux/**/bits/types/struct_shmid_ds.h
for correctness. Some arches still look like they have an incorrect
declaration but this, at least, fixes aarch64 which is the more
common one.

Signed-off-by: Andrei Horodniceanu <a.horodniceanu@proton.me>

Author: the-horo

runtime/druntime/src/core/sys/posix/sys/shm.d

@@ -66,11 +66,11 @@ version (linux)
         ipc_perm    shm_perm;
         size_t      shm_segsz;
         time_t      shm_atime;
-        version (X86_64) {} else c_ulong     __unused1;
+        static if (time_t.sizeof == 4) c_ulong     __unused1;
         time_t      shm_dtime;
-        version (X86_64) {} else c_ulong     __unused2;
+        static if (time_t.sizeof == 4) c_ulong     __unused2;
         time_t      shm_ctime;
-        version (X86_64) {} else c_ulong     __unused3;
+        static if (time_t.sizeof == 4) c_ulong     __unused3;
         pid_t       shm_cpid;
         pid_t       shm_lpid;
         shmatt_t    shm_nattch;