sys/newlib_syscalls_default: Remove MIPS-specific ifdef.

Now that MIPS is gone, the ifdef is no longer necessary.

If it eve gets added back in we should think of a more elegant way
to integrate it with the C library.

sys/newlib_syscalls_default/syscalls.c

@@ -62,8 +62,6 @@ extern char _sheap;                 /* start of the heap */
 extern char _eheap;                 /* end of the heap */
 char *heap_top = &_sheap + 4;
 
-/* MIPS newlib crt implements _init,_fini and _exit and manages the heap */
-#ifndef __mips__
 /**
  * @brief Initialize NewLib, called by __libc_init_array() from the startup script
  */
@@ -122,8 +120,6 @@ void *_sbrk_r(struct _reent *r, ptrdiff_t incr)
     return res;
 }
 
-#endif /*__mips__*/
-
 /**
  * @brief Get the process-ID of the current thread
  *