Add a test to set TCLIBC=newlib and build newlib/libgloss.
This is the absolute minimum test, but at least it exercises the build
of this package.
(From OE-Core rev: cd670fd657a54601b10e9e09a40c5b51ed4d1cf8)
Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
