tree c0b5b8f7ac3647577352371be26db914592a0331
parent 7f107feedfa42ca80928358ec6c2aa50b25fdb25
author Simon South <simon@simonsouth.net> 1570028107 -0400
committer Tom Rini <trini@konsulko.com> 1572520973 -0400

tiny-printf: Support vsnprintf()

Add a simple implementation of this function, to allow logging to be
enabled in the SPL or TPL for systems that rely on the tiny printf()
implementation.

To keep the code size small,

- The function is built only when logging is enabled, as it
  (currently) is not needed otherwise; and
- Like the existing implementation of snprintf(), its buffer-size
  parameter is ignored.

Signed-off-by: Simon South <simon@simonsouth.net>