[fusl] Remove code for unsupported architectures

fusl/src/thread/arm/__set_thread_area.c

-#include <stdint.h>
-#include <elf.h>
-#include "pthread_impl.h"
-#include "libc.h"
-
-#define HWCAP_TLS (1 << 15)
-
-extern const unsigned char __attribute__((__visibility__("hidden")))
-__a_barrier_dummy[],
-    __a_barrier_oldkuser[], __a_barrier_v6[], __a_barrier_v7[], __a_cas_dummy[],
-    __a_cas_v6[], __a_cas_v7[], __a_gettp_dummy[];
-
-#define __a_barrier_kuser 0xffff0fa0
-#define __a_cas_kuser 0xffff0fc0
-#define __a_gettp_kuser 0xffff0fe0
-
-extern uintptr_t __attribute__((__visibility__("hidden"))) __a_barrier_ptr,
-    __a_cas_ptr, __a_gettp_ptr;
-
-#define SET(op, ver) \
-  (__a_##op##_ptr = (uintptr_t)__a_##op##_##ver - (uintptr_t)__a_##op##_dummy)
-
-int __set_thread_area(void* p) {
-#if !__ARM_ARCH_7A__ && !__ARM_ARCH_7R__ && __ARM_ARCH < 7
-  if (__hwcap & HWCAP_TLS) {
-    size_t* aux;
-    SET(cas, v7);
-    SET(barrier, v7);
-    for (aux = libc.auxv; *aux; aux += 2) {
-      if (*aux != AT_PLATFORM)
-        continue;
-      const char* s = (void*)aux[1];
-      if (s[0] != 'v' || s[1] != '6' || s[2] - '0' < 10u)
-        break;
-      SET(cas, v6);
-      SET(barrier, v6);
-      break;
-    }
-  } else {
-    int ver = *(int*)0xffff0ffc;
-    SET(gettp, kuser);
-    SET(cas, kuser);
-    SET(barrier, kuser);
-    if (ver < 2)
-      a_crash();
-    if (ver < 3)
-      SET(barrier, oldkuser);
-  }
-#endif
-  return __syscall(0xf0005, p);
-}