Build: Enable C++ support during compilation

Adds support for CXX to TF-M's build system. This is required for any
secure partitions that wish to make use of C++, for example, and avoids
manual changes being applied to TF-M when C++ needs to be enabled in
projects.

Signed-off-by: Rajkumar Kanagaraj <rajkumar.kanagaraj@linaro.org>
Change-Id: Id8f9842776589a8e9315d6a1059e1330b368a45c
5 files changed