Hexagon: add PC alignment check and exception

Hexagon: add PC alignment check and exception

The Hexagon Programmer's Reference Manual says that the exception 0x1e
should be raised upon an unaligned program counter. Let's implement that
and also add some tests.

Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Taylor Simpson <ltaylorsimpson@gmail.com>
Reviewed-by: Brian Cain <bcain@quicinc.com>
Message-Id: <277b7aeda2c717a96d4dde936b3ac77707cb6517.1714755107.git.quic_mathbern@quicinc.com>
Signed-off-by: Brian Cain <bcain@quicinc.com>