trusty-libc: Pull in libc-ext

We've added libc-ext for use in both kernel and userspace to add utility
functions (like scnprintf) that are not part of a standard libc but will
allow us to write safer/better code.

This patch pulls it into libc by default.

Bug: 133358839
Change-Id: Ied984f6a0025b0070ce6c87b953596cc698bb0c0
1 file changed