Make improvements

- Polyfill readlink("foo/") dir check on Windows
- Support asynchronous signal delivery on Windows
- Restore Windows Console from execve() daisy chain
- Work around bug in AARCH64 Optimized Routines memcmp()
- Disable unbourne.com shell completion on Windows for now
- Don't always set virtual terminal input state on console
- Remove Musl Libc's unusual preservation of realpath("//")
- Make realpath() strongly link malloc() to pass configure test
- Delete cosh.com shell, now that unbourne.com works on Windows!

libc/intrin/memcmp.c

@@ -20,7 +20,6 @@
 #include "libc/intrin/likely.h"
 #include "libc/nexgen32e/x86feature.h"
 #include "libc/str/str.h"
-#ifndef __aarch64__
 
 typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(1)));
 
@@ -83,5 +82,3 @@ int memcmp(const void *a, const void *b, size_t n) {
   }
   return 0;
 }
-
-#endif /* __aarch64__ */