Backported from X.org:

commit c95c1d338fdb62dbe3dba934b97324fa778b7fce
Author: Alan Coopersmith <alan.coopersmith@oracle.com>
Date:   Sat Nov 27 18:43:12 2010 -0800

    Add asprintf() implementation for platforms without it

    Provides a portable implementation of this common allocating sprintf()
    API found in many, but not yet all, of the platforms we support.
    If the platform provides vasprintf() we simply wrap it, otherwise we
    implement it - either way callers can use it regardless of platform.

    Since not all platforms guarantee to NULL out the return pointer on
    failure, we don't either, and require callers to check the return
    value for -1.

    The old Xprintf() API is deprecated, but left for compatibility for now.

    The new API is added in a new header so that it can be used in parts of
    the server such as hw/xfree86/parser that don't include all the server
    headers.
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Mikhail Gusarov <dottedmag@dottedmag.net>

Includes re-indentation changes from
9838b7032ea9792bec21af424c53c07078636d21.
Backported-to-NX-by: Mihai Moldovan <ionic@ionic.de>