target/hexagon: import lexer for idef-parser

Signed-off-by: Alessandro Di Federico <ale@rev.ng>
Signed-off-by: Paolo Montesel <babush@rev.ng>
Signed-off-by: Anton Johansson <anjo@rev.ng>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20220923173831.227551-9-anjo@rev.ng>