Improve Windows mode bits

We were too zealous about security before by only setting the owner bits
and that would cause issues for projects like redbean that check "other"
bits to determine if it's safe to serve a file. Since that doesn't exist
on Windows, it's better to have things work than not work. So what we'll
do instead is return modes like 0664 for files and 0775 for directories.

libc/intrin/umask.c

@@ -19,4 +19,4 @@
 #include "libc/atomic.h"
 #include "libc/calls/internal.h"
 
-atomic_int __umask;
+atomic_int __umask = 0777;