tests/tcg: disable xtensa-linux-user again

tests/tcg: disable xtensa-linux-user again

The move from tests/tcg/configure.sh started enabling the container image
for xtensa-linux-user, which fails because the compiler does not have
the full set of headers.  The cause is the "xtensa*-softmmu)" case
in tests/tcg/configure.sh which became just "xtensa*)" in the new
probe_target_compiler shell function.  Look out for xtensa*-linux-user
and do not configure it.

Reported-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220608135727.1341946-1-pbonzini@redhat.com>
Fixes: cd362defbb ("tests/tcg: merge configure.sh back into main configure script")
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220613171258.1905715-6-alex.bennee@linaro.org>