tests/tcg/multiarch: enable additional linux-test tests

tests/tcg/multiarch: enable additional linux-test tests

Un-comment the remaining tests.

I removed the itimer value tests because I'm fairly sure a re-arming
timer will always have a different value in it when you grab it.

I've also fixed up the clone thread flags as QEMU will only allow a
clone to use flags which match glibc. However the test is still racey
so it remains disabled by default - it can be run by passing any
additional parameters on the command line.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>