The read()/write() functions still work without VFS when
reading/writing to stdin, stdout or stderr.
Provide dummy functions for the remaining fs functions so
linking does not fail with !VFS.
picolibc: Use thread_getpid for getpid() in picolibc_syscalls_default
Instead of directly accessing the sched_active_pid variable (which
isn't defined in this context), use the existing wrapper function
to get that value.
Signed-off-by: Keith Packard <keithp@keithp.com>
---
v2:
Squash a couple of fixes in
* fixup! picolibc: Use thread_getpid for getpid() in
picolibc_syscalls_default
* squashme: Add `times` to picolibc syscalls
* Add __noreturn__ attribute to _exit
* Add VFS syscall wrappers. This provides the POSIX api used
by picolibc stdio
