common-user: Really fix i386 calls to safe_syscall_set_errno_tail

Brown bag time: offset 0 from esp is the return address,
offset 4 is the first argument.

Fixes: d7478d4229f0 ("common-user: Fix tail calls to safe_syscall_set_errno_tail")
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

common-user/host/i386/safe-syscall.inc.S

@@ -120,7 +120,7 @@ safe_syscall_end:
         pop     %ebp
         .cfi_adjust_cfa_offset -4
         .cfi_restore ebp
-        mov     %eax, (%esp)
+        mov     %eax, 4(%esp)
         jmp     safe_syscall_set_errno_tail
 
         .cfi_endproc