[fusl] Remove code for unsupported architectures

fusl/arch/i386/bits/user.h

-#undef __WORDSIZE
-#define __WORDSIZE 32
-
-typedef struct user_fpregs_struct {
-  long cwd, swd, twd, fip, fcs, foo, fos, st_space[20];
-} elf_fpregset_t;
-
-typedef struct user_fpxregs_struct {
-  unsigned short cwd, swd, twd, fop;
-  long fip, fcs, foo, fos, mxcsr, reserved;
-  long st_space[32], xmm_space[32], padding[56];
-} elf_fpxregset_t;
-
-struct user_regs_struct {
-  long ebx, ecx, edx, esi, edi, ebp, eax, xds, xes, xfs, xgs;
-  long orig_eax, eip, xcs, eflags, esp, xss;
-};
-
-#define ELF_NGREG 17
-typedef unsigned long elf_greg_t, elf_gregset_t[ELF_NGREG];
-
-struct user {
-  struct user_regs_struct regs;
-  int u_fpvalid;
-  struct user_fpregs_struct i387;
-  unsigned long u_tsize;
-  unsigned long u_dsize;
-  unsigned long u_ssize;
-  unsigned long start_code;
-  unsigned long start_stack;
-  long signal;
-  int reserved;
-  struct user_regs_struct* u_ar0;
-  struct user_fpregs_struct* u_fpstate;
-  unsigned long magic;
-  char u_comm[32];
-  int u_debugreg[8];
-};
-
-#define PAGE_MASK (~(PAGE_SIZE - 1))
-#define NBPG PAGE_SIZE
-#define UPAGES 1
-#define HOST_TEXT_START_ADDR (u.start_code)
-#define HOST_STACK_END_ADDR (u.start_stack + u.u_ssize * NBPG)