tcg/LICENSE: Remove out of date claim about TCG subdirectory licensing

tcg/LICENSE: Remove out of date claim about TCG subdirectory licensing

Since 2008 the tcg/LICENSE file has not changed: it claims that
everything under tcg/ is BSD-licensed.

This is not true and hasn't been true for years: in 2013 we
accepted the tcg/aarch64 target code under a GPLv2-or-later
license statement. We also have generic vector optimisation
code under the LGPL2.1-or-later, and the TCI backend is
GPLv2-or-later. Further, many of the files are not BSD
licensed but MIT licensed.

We don't really consider the tcg subdirectory to be a distinct part
of QEMU anyway.

Remove the LICENSE file, since claiming false information
about the license of the code is confusing.

Update the main project LICENSE file also to be clearer about
the licenses used by TCG.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20191025155848.17362-5-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>