Merge the final components for Aarch64 support into master.

Create the wctype crate and stub functions with the unimplemented macro.

Add ctype functions
  - isalnum
  - isalpha
  - isascii
  - isdigit
  - islower
  - isspace
  - isupper
Add stdlib functions
  - atoi
  - atol
Fix some warnings
Make a fmt run

Dan Robertson authored 7 years ago and Dan Robertson committed 7 years ago

 - Add aarch64 support
   - crt0 - add support to _start
   - platform - aarch64 does not have the open syscall. Instead most
     libc implementations use openat() with AT_FDCWD
 - Use sc instead of syscall. sc is the maintained fork of syscall.